diff --git a/zebrad/src/components/mempool.rs b/zebrad/src/components/mempool.rs
index 0c38da71..1ec888e5 100644
--- a/zebrad/src/components/mempool.rs
+++ b/zebrad/src/components/mempool.rs
@@ -1,5 +1,8 @@
 //! Zebra mempool.
 
+/// Mempool-related errors.
+pub mod error;
+
 mod crawler;
 
 pub use self::crawler::Crawler;
diff --git a/zebrad/src/components/mempool/error.rs b/zebrad/src/components/mempool/error.rs
new file mode 100644
index 00000000..f3a47406
--- /dev/null
+++ b/zebrad/src/components/mempool/error.rs
@@ -0,0 +1,25 @@
+//! Errors that can occur when manipulating transactions in the mempool.
+
+use thiserror::Error;
+
+#[derive(Error, Clone, Debug, PartialEq)]
+#[allow(dead_code)]
+pub enum MempoolError {
+    #[error("transaction already exists in mempool")]
+    InMempool,
+
+    #[error("transaction did not pass consensus validation")]
+    Invalid(#[from] zebra_consensus::error::TransactionError),
+
+    #[error("transaction is committed in block {0:?}")]
+    InBlock(zebra_chain::block::Hash),
+
+    #[error("transaction has expired")]
+    Expired,
+
+    #[error("transaction fee is too low for the current mempool state")]
+    LowFee,
+
+    #[error("transaction was not found in mempool")]
+    NotInMempool,
+}