diff --git a/src/bin/client.rs b/src/bin/client.rs
index a862737be..19ae5bfd8 100644
--- a/src/bin/client.rs
+++ b/src/bin/client.rs
@@ -53,7 +53,9 @@ impl IoHandler<NetSyncMessage> for ClientIoHandler {
 
 	fn timeout<'s>(&'s mut self, _io: &mut IoContext<'s, NetSyncMessage>, timer: TimerToken) {
 		if self.timer == timer {
-			println!("Chain info: {:?}", self.client.read().unwrap().deref().chain_info());
+			self.client.tick();
+			println!("Chain info: {}", self.client.read().unwrap().deref().chain_info());
+			println!("Cache info: {:?}", self.client.read().unwrap().deref().cache_info());
 		}
 	}
 }
diff --git a/src/blockchain.rs b/src/blockchain.rs
index b55b71fdb..d0b97a0ff 100644
--- a/src/blockchain.rs
+++ b/src/blockchain.rs
@@ -30,6 +30,11 @@ pub struct CacheSize {
 	pub blocks_blooms: usize
 }
 
+impl CacheSize {
+	/// Total amount used by the cache.
+	fn total(&self) -> usize { self.blocks + self.block_details + self.transaction_addresses + self.block_logs + self.blocks_blooms }
+}
+
 /// Information about best block gathered together
 struct BestBlock {
 	pub hash: H256,
@@ -97,9 +102,9 @@ pub trait BlockProvider {
 }
 
 #[derive(Debug, Hash, Eq, PartialEq, Clone)]
-struct CacheID {
-	id: H256,
-	extra: usize
+enum CacheID {
+	Block(H256),
+	Extras(ExtrasIndex, H256),
 }
 
 struct CacheManager {
@@ -149,6 +154,8 @@ impl BlockProvider for BlockChain {
 		let opt = self.blocks_db.get(hash)
 			.expect("Low level database error. Some issue with disk?");
 
+		self.note_used(CacheID::Block(hash.clone()));
+
 		match opt {
 			Some(b) => {
 				let bytes: Bytes = b.to_vec();
@@ -214,6 +221,9 @@ impl BlockChain {
 		blocks_path.push("blocks");
 		let blocks_db = DB::open_default(blocks_path.to_str().unwrap()).unwrap();
 
+		let mut cache_man = CacheManager{cache_usage: VecDeque::new(), in_use: HashSet::new()};
+		(0..COLLECTION_QUEUE_SIZE).foreach(|_| cache_man.cache_usage.push_back(HashSet::new()));
+
 		let bc = BlockChain {
 			best_block: RwLock::new(BestBlock::new()),
 			blocks: RwLock::new(HashMap::new()),
@@ -224,7 +234,7 @@ impl BlockChain {
 			blocks_blooms: RwLock::new(HashMap::new()),
 			extras_db: extras_db,
 			blocks_db: blocks_db,
-			cache_man: RwLock::new(CacheManager{cache_usage: VecDeque::new(), in_use: HashSet::new()}),
+			cache_man: RwLock::new(cache_man),
 		};
 
 		// load best block
@@ -515,6 +525,10 @@ impl BlockChain {
 			}
 		}
 
+		if let Some(h) = hash.as_h256() {
+			self.note_used(CacheID::Extras(T::extras_index(), h.clone()));
+		}
+
 		self.extras_db.get_extras(hash).map(| t: T | {
 			let mut write = cache.write().unwrap();
 			write.insert(hash.clone(), t.clone());
@@ -556,21 +570,54 @@ impl BlockChain {
 		self.blocks_blooms.write().unwrap().squeeze(size.blocks_blooms);
 	}
 
+	/// Let the cache system know that a cacheable item has been used.
 	fn note_used(&self, id: CacheID) {
 		let mut cache_man = self.cache_man.write().unwrap();
-		cache_man.cache_usage[0].insert(id.clone());
-		// TODO: check more than just the first?
-		if cache_man.cache_usage[1].contains(&id) {
-			cache_man.cache_usage[1].remove(&id);
-		}
-		else {
-			cache_man.in_use.insert(id);
+		if !cache_man.cache_usage[0].contains(&id) {
+			cache_man.cache_usage[0].insert(id.clone());
+			if cache_man.in_use.contains(&id) {
+				if let Some(c) = cache_man.cache_usage.iter_mut().skip(1).find(|e|e.contains(&id)) {
+					c.remove(&id);
+				}
+			} else {
+				cache_man.in_use.insert(id);
+			}
 		}
 	}
 
 	/// Ticks our cache system and throws out any old data.
-	pub fn tick(&self) {
+	pub fn collect_garbage(&self, force: bool) {
+		// TODO: check time.
+		let timeout = true;
 
+		let t = self.cache_size().total();
+		if t < MIN_CACHE_SIZE || (!timeout && (!force || t < MAX_CACHE_SIZE)) { return; }
+
+		let mut cache_man = self.cache_man.write().unwrap();
+		let mut blocks = self.blocks.write().unwrap();
+		let mut block_details = self.block_details.write().unwrap();
+		let mut block_hashes = self.block_hashes.write().unwrap();
+		let mut transaction_addresses = self.transaction_addresses.write().unwrap();
+		let mut block_logs = self.block_logs.write().unwrap();
+		let mut blocks_blooms = self.blocks_blooms.write().unwrap();
+
+		for id in cache_man.cache_usage.pop_back().unwrap().into_iter() {
+			cache_man.in_use.remove(&id);
+			match id {
+				CacheID::Block(h) => { blocks.remove(&h); },
+				CacheID::Extras(ExtrasIndex::BlockDetails, h) => { block_details.remove(&h); },
+				CacheID::Extras(ExtrasIndex::TransactionAddress, h) => { transaction_addresses.remove(&h); },
+				CacheID::Extras(ExtrasIndex::BlockLogBlooms, h) => { block_logs.remove(&h); },
+				CacheID::Extras(ExtrasIndex::BlocksBlooms, h) => { blocks_blooms.remove(&h); },
+				_ => panic!(),
+			}
+		}
+		cache_man.cache_usage.push_front(HashSet::new());
+
+		// TODO: handle block_hashes properly.
+		block_hashes.clear();
+
+		// TODO: m_lastCollection = chrono::system_clock::now();
 	}
 }
 
diff --git a/src/client.rs b/src/client.rs
index dc8bf3608..0d9e94606 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,6 +1,6 @@
 use util::*;
 use rocksdb::{Options, DB};
-use blockchain::{BlockChain, BlockProvider};
+use blockchain::{BlockChain, BlockProvider, CacheSize};
 use views::BlockView;
 use error::*;
 use header::BlockNumber;
@@ -40,6 +40,12 @@ pub struct BlockChainInfo {
 	pub best_block_number: BlockNumber
 }
 
+impl fmt::Display for BlockChainInfo {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write!(f, "#{}.{}", self.best_block_number, self.best_block_hash)
+	}
+}
+
 /// Block queue status
 #[derive(Debug)]
 pub struct BlockQueueStatus {
@@ -208,6 +214,16 @@ impl Client {
 		}
 		debug!(target: "client", "Imported #{} ({})", header.number(), header.hash());
 	}
+
+	/// Get info on the cache.
+	pub fn cache_info(&self) -> CacheSize {
+		self.chain.read().unwrap().cache_size()
+	}
+
+	/// Tick the client.
+	pub fn tick(&self) {
+		self.chain.read().unwrap().collect_garbage(false);
+	}
 }
 
 impl BlockChainClient for Client {
diff --git a/src/extras.rs b/src/extras.rs
index ed0032698..8052af791 100644
--- a/src/extras.rs
+++ b/src/extras.rs
@@ -3,7 +3,7 @@ use header::BlockNumber;
 use rocksdb::{DB, Writable};
 
 /// Represents index of extra data in database
-#[derive(Copy, Clone)]
+#[derive(Copy, Debug, Hash, Eq, PartialEq, Clone)]
 pub enum ExtrasIndex {
 	BlockDetails = 0,
 	BlockHash = 1,
@@ -59,6 +59,7 @@ impl ExtrasReadable for DB {
 /// Implementations should convert arbitrary type to database key slice
 pub trait ExtrasSliceConvertable {
 	fn to_extras_slice(&self, i: ExtrasIndex) -> H264;
+	fn as_h256(&self) -> Option<&H256> { None }
 }
 
 impl ExtrasSliceConvertable for H256 {
@@ -67,6 +68,7 @@ impl ExtrasSliceConvertable for H256 {
 		slice[32] = i as u8;
 		slice
 	}
+	fn as_h256(&self) -> Option<&H256> { Some(self) }
 }
 
 impl ExtrasSliceConvertable for U256 {