diff --git a/src/com/eldrix/hermes/core.clj b/src/com/eldrix/hermes/core.clj
index 83ca268..10c23d7 100644
--- a/src/com/eldrix/hermes/core.clj
+++ b/src/com/eldrix/hermes/core.clj
@@ -697,12 +697,24 @@
   :args (s/cat :svc ::svc :concept-ids (s/coll-of :info.snomed.Concept/id) :ecl ::non-blank-string))
 (defn intersect-ecl
   "Returns the subset of the concept identifiers that satisfy the SNOMED ECL
-  expression."
+  expression. Use [[intersect-ecl-fn]] if the same ECL expression will be
+  used repeatedly."
   [^Svc svc concept-ids ^String ecl]
   (let [q1 (search/q-concept-ids concept-ids)
         q2 (ecl/parse svc ecl)]
     (search/do-query-for-concept-ids (.-searcher svc) (search/q-and [q1 q2]))))
 
+(s/fdef intersect-ecl-fn
+  :args (s/cat :svc ::svc :ecl ::non-blank-string))
+(defn intersect-ecl-fn
+  "Return a function that can return the subset the specified concept
+  identifiers that satisfy the SNOMED ECL expression."
+  [^Svc svc ^String ecl]
+  (let [q2 (ecl/parse svc ecl)]
+    (fn [concept-ids]
+      (let [q1 (search/q-concept-ids concept-ids)]
+        (search/do-query-for-concept-ids (.-searcher svc) (search/q-and [q1 q2]))))))
+
 (s/fdef valid-ecl?
   :args (s/cat :s string?))
 (defn valid-ecl?
diff --git a/test/src/com/eldrix/hermes/core_test.clj b/test/src/com/eldrix/hermes/core_test.clj
index 1ab35b8..2a8fdca 100644
--- a/test/src/com/eldrix/hermes/core_test.clj
+++ b/test/src/com/eldrix/hermes/core_test.clj
@@ -50,12 +50,18 @@
 
 (deftest ^:live test-intersect-ecl
   (is (= #{24700007} (hermes/intersect-ecl *svc* [24700007] "<<24700007")) "Descendant or self expression should include self")
+  (is (= #{24700007} ((hermes/intersect-ecl-fn *svc* "<<24700007") [24700007])) "Descendant or self expression should include self")
   (is (= #{816984002} (hermes/intersect-ecl *svc* [816984002] "<<24700007")) "Primary progressive multiple sclerosis is a type of MS")
+  (is (= #{816984002} ((hermes/intersect-ecl-fn *svc* "<<24700007") [816984002])) "Primary progressive multiple sclerosis is a type of MS")
   (is (= #{24700007} (hermes/intersect-ecl *svc* [24700007] "^447562003")) "Multiple sclerosis should be in the ICD-10 complex map reference set")
+  (is (= #{24700007} ((hermes/intersect-ecl-fn *svc* "^447562003") [24700007])) "Multiple sclerosis should be in the ICD-10 complex map reference set")
   (is (= #{24700007} (hermes/intersect-ecl *svc* #{315560000 24700007} "<64572001")) "Born in Wales is not a type of disease")
+  (is (= #{24700007} ((hermes/intersect-ecl-fn *svc* "<64572001") #{315560000 24700007})) "Born in Wales is not a type of disease")
   (let [concept-ids-1 (set (map :conceptId (hermes/search *svc* {:s "m"})))
-        concept-ids-2 (hermes/intersect-ecl *svc* concept-ids-1 "<<138875005")]
-    (is (empty? (set/difference concept-ids-1 concept-ids-2)) "All concepts should be children of root SNOMED CT")))
+        concept-ids-2 (hermes/intersect-ecl *svc* concept-ids-1 "<<138875005")
+        concept-ids-3 ((hermes/intersect-ecl-fn *svc* "<<138875005") concept-ids-1)]
+    (is (empty? (set/difference concept-ids-1 concept-ids-2)) "All concepts should be children of root SNOMED CT")
+    (is (empty? (set/difference concept-ids-1 concept-ids-3)) "All concepts should be children of root SNOMED CT")))
 
 (deftest ^:live test-expand-historic
   (is (every? true? (->> (hermes/expand-ecl *svc* "<<24700007")
@@ -101,8 +107,6 @@
     (is (seq (filter #{"Appendicectomy"} (map :term r2))) "Appendicectomy should be a preferred term for en-GB locale")
     (is (seq (filter #{"Appendectomy"} (map :term r3))) "Appendectomy should be a preferred term for en-US locale")))
 
-
-
 (deftest ^:live test-with-historical
   (is (:active (hermes/concept *svc* 24700007)))
   (is (not (:active (hermes/concept *svc* 586591000000100))))