diff --git a/chaincfg/mainnetparams.go b/chaincfg/mainnetparams.go
index bfd30239..4a365d53 100644
--- a/chaincfg/mainnetparams.go
+++ b/chaincfg/mainnetparams.go
@@ -116,6 +116,16 @@ func MainNetParams() *Params {
 			{601900, newHashFromStr("00000000000000001c1865a45a038bb680fc076d70cd88c1843e3e669cb54942")},
 		},
 
+		// AssumeValid is the hash of a block that has been externally verified
+		// to be valid.  It allows several validation checks to be skipped for
+		// blocks that are both an ancestor of the assumed valid block and an
+		// ancestor of the best header.  This is intended to be updated
+		// periodically with new releases.
+		//
+		// Block 00000000000000001251efb83ad1a5c71351b50fe9195f009cf0bf5a7cd99d52
+		// Height: 606000
+		AssumeValid: *newHashFromStr("00000000000000001251efb83ad1a5c71351b50fe9195f009cf0bf5a7cd99d52"),
+
 		// MinKnownChainWork is the minimum amount of known total work for the
 		// chain at a given point in time.  This is intended to be updated
 		// periodically with new releases.
diff --git a/chaincfg/params.go b/chaincfg/params.go
index c19f050f..1ce05356 100644
--- a/chaincfg/params.go
+++ b/chaincfg/params.go
@@ -335,6 +335,13 @@ type Params struct {
 	// will likely be changed to only allow a single checkpoint in the future.
 	Checkpoints []Checkpoint
 
+	// AssumeValid is the hash of a block that has been externally verified to
+	// be valid.  It allows several validation checks to be skipped for blocks
+	// that are both an ancestor of the assumed valid block and an ancestor of
+	// the best header.  This is intended to be updated periodically with new
+	// releases.  It may not be set for networks that do not require it.
+	AssumeValid chainhash.Hash
+
 	// MinKnownChainWork is the minimum amount of known total work for the chain
 	// at a given point in time.  This is intended to be updated periodically
 	// with new releases.  It may be nil for networks that do not require it.
diff --git a/chaincfg/regnetparams.go b/chaincfg/regnetparams.go
index e4aa30ff..8f2cf9fe 100644
--- a/chaincfg/regnetparams.go
+++ b/chaincfg/regnetparams.go
@@ -112,6 +112,12 @@ func RegNetParams() *Params {
 		// Checkpoints ordered from oldest to newest.
 		Checkpoints: nil,
 
+		// AssumeValid is the hash of a block that has been externally verified
+		// to be valid.
+		//
+		// Not set for regression test network since its chain is dynamic.
+		AssumeValid: chainhash.Hash{},
+
 		// MinKnownChainWork is the minimum amount of known total work for the
 		// chain at a given point in time.
 		//
diff --git a/chaincfg/simnetparams.go b/chaincfg/simnetparams.go
index 43763ad6..a18e5a79 100644
--- a/chaincfg/simnetparams.go
+++ b/chaincfg/simnetparams.go
@@ -111,6 +111,12 @@ func SimNetParams() *Params {
 		// Checkpoints ordered from oldest to newest.
 		Checkpoints: nil,
 
+		// AssumeValid is the hash of a block that has been externally verified
+		// to be valid.
+		//
+		// Not set for simnet test network since its chain is dynamic.
+		AssumeValid: chainhash.Hash{},
+
 		// MinKnownChainWork is the minimum amount of known total work for the
 		// chain at a given point in time.
 		//
diff --git a/chaincfg/testnetparams.go b/chaincfg/testnetparams.go
index 5cdb15ba..5416c35b 100644
--- a/chaincfg/testnetparams.go
+++ b/chaincfg/testnetparams.go
@@ -111,6 +111,16 @@ func TestNet3Params() *Params {
 			{803810, newHashFromStr("000000016e841f4d94c3b253bc7bdf3a13217c7f28a5935bbaec37c7752678e9")},
 		},
 
+		// AssumeValid is the hash of a block that has been externally verified
+		// to be valid.  It allows several validation checks to be skipped for
+		// blocks that are both an ancestor of the assumed valid block and an
+		// ancestor of the best header.  This is intended to be updated
+		// periodically with new releases.
+		//
+		// Block 00000000d64ceb1a686315ed56235e9a6838e3a22e9ec9bd92c2e04c09e0778b
+		// Height: 807905
+		AssumeValid: *newHashFromStr("00000000d64ceb1a686315ed56235e9a6838e3a22e9ec9bd92c2e04c09e0778b"),
+
 		// MinKnownChainWork is the minimum amount of known total work for the
 		// chain at a given point in time.  This is intended to be updated
 		// periodically with new releases.