diff --git a/pkg/sql/as_of_test.go b/pkg/sql/as_of_test.go
index d162a644e072..be76490ab985 100644
--- a/pkg/sql/as_of_test.go
+++ b/pkg/sql/as_of_test.go
@@ -161,7 +161,7 @@ func TestAsOfTime(t *testing.T) {
 	}
 
 	// String values that are neither timestamps nor decimals are an error.
-	if _, err := db.Query("SELECT a FROM d.t AS OF SYSTEM TIME 'xxx'"); !testutils.IsError(err, "value is neither timestamp nor decimal") {
+	if _, err := db.Query("SELECT a FROM d.t AS OF SYSTEM TIME 'xxx'"); !testutils.IsError(err, "value is neither timestamp, decimal, nor interval") {
 		t.Fatal(err)
 	}
 
diff --git a/pkg/sql/executor.go b/pkg/sql/executor.go
index 96e8b5d8f5e6..5cee83db26ab 100644
--- a/pkg/sql/executor.go
+++ b/pkg/sql/executor.go
@@ -2480,20 +2480,24 @@ func EvalAsOfTimestamp(
 			break
 		}
 		// Attempt to parse as a decimal.
-		if dec, _, err := apd.NewFromString(s); err != nil {
-			// Override the error. It would be misleading to fail with a
-			// DECIMAL conversion error if a user was attempting to use a
-			// timestamp string and the conversion above failed.
-			convErr = errors.Errorf("AS OF SYSTEM TIME: value is neither timestamp nor decimal")
-		} else {
+		if dec, _, err := apd.NewFromString(s); err == nil {
 			ts, convErr = decimalToHLC(dec)
+			break
+		}
+		// Attempt to parse as an interval.
+		if iv, err := tree.ParseDInterval(s); err == nil {
+			ts.WallTime = duration.Add(evalCtx.GetStmtTimestamp(), iv.Duration).UnixNano()
+			break
 		}
+		convErr = errors.Errorf("AS OF SYSTEM TIME: value is neither timestamp, decimal, nor interval")
 	case *tree.DInt:
 		ts.WallTime = int64(*d)
 	case *tree.DDecimal:
 		ts, convErr = decimalToHLC(&d.Decimal)
+	case *tree.DInterval:
+		ts.WallTime = duration.Add(evalCtx.GetStmtTimestamp(), d.Duration).UnixNano()
 	default:
-		convErr = errors.Errorf("AS OF SYSTEM TIME: expected timestamp, got %s (%T)", d.ResolvedType(), d)
+		convErr = errors.Errorf("AS OF SYSTEM TIME: expected timestamp, decimal, or interval, got %s (%T)", d.ResolvedType(), d)
 	}
 	if convErr != nil {
 		return ts, convErr
diff --git a/pkg/sql/logictest/testdata/logic_test/as_of b/pkg/sql/logictest/testdata/logic_test/as_of
new file mode 100644
index 000000000000..2c962dc1c6d5
--- /dev/null
+++ b/pkg/sql/logictest/testdata/logic_test/as_of
@@ -0,0 +1,30 @@
+# LogicTest: default
+
+statement ok
+CREATE TABLE t (i INT)
+
+statement ok
+INSERT INTO t VALUES (2)
+
+# Verify strings can be parsed as intervals.
+query I
+SELECT * FROM t AS OF SYSTEM TIME '-0ns'
+----
+2
+
+query I
+SELECT * FROM t AS OF SYSTEM TIME '-1ns'
+----
+2
+
+# Verify a forced interval type works.
+query I
+SELECT * FROM t AS OF SYSTEM TIME INTERVAL '-1ns'
+----
+2
+
+statement error pq: relation "t" does not exist
+SELECT * FROM t AS OF SYSTEM TIME '-1h'
+
+statement error cannot specify timestamp in the future
+SELECT * FROM t AS OF SYSTEM TIME '10s'