diff --git a/CHANGELOG.md b/CHANGELOG.md
index 351a4c2..1cff242 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Changes
 
 * 2.6.next in progress
+  * Address [#567](https://github.com/seancorfield/honeysql/issues/567) by adding support for `ASSERT` clause.
   * Address [#566](https://github.com/seancorfield/honeysql/issues/566) by adding `IS [NOT] DISTINCT FROM` operators.
   * Add examples of `:alias` with `:group-by` (syntax is slightly different to existing examples for `:order-by`).
 
diff --git a/doc/xtdb.md b/doc/xtdb.md
index 3f11274..709ebee 100644
--- a/doc/xtdb.md
+++ b/doc/xtdb.md
@@ -207,3 +207,14 @@ user=> (sql/format {:patch-into :foo
                     :records [{:_id 1 :status "active"}]})
 ["PATCH INTO foo RECORDS ?" {:_id 1, :status "active"}]
 ```
+
+## `assert`
+
+XTDB supports an `ASSERT` operation that will throw an exception if the
+asserted predicate is not true:
+
+```clojure
+user=> (sql/format '{assert (not-exists {select 1 from users where (= email "james @example.com")})}
+                   :inline true)
+["ASSERT NOT EXISTS (SELECT 1 FROM users WHERE email = 'james @example.com')"]
+```
diff --git a/src/honey/sql.cljc b/src/honey/sql.cljc
index 642fdf7..174d379 100644
--- a/src/honey/sql.cljc
+++ b/src/honey/sql.cljc
@@ -59,7 +59,7 @@
    ;; then SQL clauses in priority order:
    :setting
    :raw :nest :with :with-recursive :intersect :union :union-all :except :except-all
-   :table
+   :table :assert ; #567 XTDB
    :select :select-distinct :select-distinct-on :select-top :select-distinct-top
    :distinct :expr :exclude :rename
    :into :bulk-collect-into
@@ -1654,6 +1654,9 @@
          :except          #'format-on-set-op
          :except-all      #'format-on-set-op
          :table           #'format-selector
+         :assert          (fn [k xs]
+                            (let [[sql & params] (format-expr xs)]
+                              (into [(str (sql-kw k) " " sql)] params)))
          :select          #'format-selects
          :select-distinct #'format-selects
          :select-distinct-on #'format-selects-on
diff --git a/test/honey/sql/xtdb_test.cljc b/test/honey/sql/xtdb_test.cljc
index d9a8c35..fb759db 100644
--- a/test/honey/sql/xtdb_test.cljc
+++ b/test/honey/sql/xtdb_test.cljc
@@ -1,4 +1,4 @@
-;; copyright (c) 2020-2024 sean corfield, all rights reserved
+;; copyright (c) 2020-2025 sean corfield, all rights reserved
 
 (ns honey.sql.xtdb-test
   (:require [clojure.test :refer [deftest is testing]]
@@ -129,3 +129,11 @@
          (sql/format '{select (((get-in (. a b) c (lift 1) d)))})))
   (is (= ["SELECT (OBJECT (_id: 1, b: 'thing').b).c[?].d" 1]
          (sql/format '{select (((get-in (. (object {_id 1 b "thing"}) b) c (lift 1) d)))}))))
+
+(deftest assert-statement
+  (is (= ["ASSERT NOT EXISTS (SELECT 1 FROM users WHERE email = 'james @example.com')"]
+         (sql/format '{assert (not-exists {select 1 from users where (= email "james @example.com")})}
+                     :inline true)))
+  (is (= ["ASSERT TRUE"]
+         (sql/format '{assert true}
+                     :inline true))))