diff --git a/src/main/java/io/reactivex/rxjava3/core/Observable.java b/src/main/java/io/reactivex/rxjava3/core/Observable.java
index b226ae8994..a4b07af049 100644
--- a/src/main/java/io/reactivex/rxjava3/core/Observable.java
+++ b/src/main/java/io/reactivex/rxjava3/core/Observable.java
@@ -7112,39 +7112,6 @@ public final <U> Observable<U> concatMapIterable(@NonNull Function<? super T, ?
         return RxJavaPlugins.onAssembly(new ObservableFlattenIterable<>(this, mapper));
     }
 
-    /**
-     * Returns an {@code Observable} that concatenate each item emitted by the current {@code Observable} with the values in an
-     * {@link Iterable} corresponding to that item that is generated by a selector.
-     * <p>
-     * <img width="640" height="275" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/concatMapIterable.o.png" alt="">
-     *
-     * <dl>
-     *  <dt><b>Scheduler:</b></dt>
-     *  <dd>{@code concatMapIterable} does not operate by default on a particular {@link Scheduler}.</dd>
-     * </dl>
-     *
-     * @param <U>
-     *            the type of item emitted by the resulting {@code Observable}
-     * @param mapper
-     *            a function that returns an {@code Iterable} sequence of values for when given an item emitted by the
-     *            current {@code Observable}
-     * @param bufferSize
-     *            the number of elements expected from the current {@code Observable} to be buffered
-     * @return an {@code Observable} that emits the results of concatenating the items emitted by the current {@code Observable} with
-     *         the values in the {@code Iterable}s corresponding to those items
-     * @throws NullPointerException if {@code mapper} is {@code null}
-     * @throws IllegalArgumentException if {@code bufferSize} is non-positive
-     * @see <a href="http://reactivex.io/documentation/operators/flatmap.html">ReactiveX operators documentation: FlatMap</a>
-     */
-    @CheckReturnValue
-    @SchedulerSupport(SchedulerSupport.NONE)
-    @NonNull
-    public final <U> Observable<U> concatMapIterable(@NonNull Function<? super T, ? extends Iterable<? extends U>> mapper, int bufferSize) {
-        Objects.requireNonNull(mapper, "mapper is null");
-        ObjectHelper.verifyPositive(bufferSize, "bufferSize");
-        return concatMap(ObservableInternalHelper.flatMapIntoIterable(mapper), bufferSize);
-    }
-
     /**
      * Maps the upstream items into {@link MaybeSource}s and subscribes to them one after the
      * other succeeds or completes, emits their success value if available or terminates immediately if
diff --git a/src/test/java/io/reactivex/rxjava3/internal/operators/observable/ObservableConcatTest.java b/src/test/java/io/reactivex/rxjava3/internal/operators/observable/ObservableConcatTest.java
index b1c42a1175..90e3dc112b 100644
--- a/src/test/java/io/reactivex/rxjava3/internal/operators/observable/ObservableConcatTest.java
+++ b/src/test/java/io/reactivex/rxjava3/internal/operators/observable/ObservableConcatTest.java
@@ -879,7 +879,7 @@ public void concatMapIterableBufferSize() {
             public Iterable<Integer> apply(Integer v) throws Exception {
                 return Arrays.asList(1, 2, 3, 4, 5);
             }
-        }, 1)
+        })
         .test()
         .assertResult(1, 2, 3, 4, 5, 1, 2, 3, 4, 5);
     }