diff --git a/include/nuttx/mm/mempool.h b/include/nuttx/mm/mempool.h
index 22366157c3..b85795207d 100644
--- a/include/nuttx/mm/mempool.h
+++ b/include/nuttx/mm/mempool.h
@@ -423,64 +423,6 @@ FAR void *mempool_multiple_memalign(FAR struct mempool_multiple_s *mpool,
 void mempool_multiple_memdump(FAR struct mempool_multiple_s *mpool,
                               pid_t pid);
 
-/****************************************************************************
- * Name: mempool_multiple_fixed_alloc
- *
- * Description:
- *   Allocate an block from specific multiple memory pool.
- *   If the mempool of the corresponding size doesn't have free block,
- *   then wait until free happened or return NULL.
- *
- * Input Parameters:
- *   mpool - The handle of multiple memory pool to be used.
- *   size  - The size of alloc blk.
- *
- * Returned Value:
- *   The pointer to the allocated block on success; NULL on any failure.
- *
- ****************************************************************************/
-
-FAR void *mempool_multiple_fixed_alloc(FAR struct mempool_multiple_s *mpool,
-                                       size_t size);
-
-/****************************************************************************
- * Name: mempool_multiple_fixed_realloc
- *
- * Description:
- *   Change the size of the block memory pointed to by oldblk to size bytes.
- *
- * Input Parameters:
- *   mpool   - The handle of multiple memory pool to be used.
- *   oldblk  - The pointer to change the size of the block memory.
- *   oldsize - The size of block memory to oldblk.
- *   size    - The size of alloc blk.
- *
- * Returned Value:
- *   The pointer to the allocated block on success; NULL on any failure.
- *
- ****************************************************************************/
-
-FAR void *
-mempool_multiple_fixed_realloc(FAR struct mempool_multiple_s *mpool,
-                               FAR void *oldblk, size_t oldsize,
-                               size_t size);
-
-/****************************************************************************
- * Name: mempool_multiple_fixed_free
- *
- * Description:
- *   Release an memory block to the multiple mempry pool. The blk must have
- *   been returned by a previous call to mempool_multiple_fixed_alloc.
- *
- * Input Parameters:
- *   mpool - The handle of multiple memory pool to be used.
- *   blk   - The pointer of memory block.
- *   size  - The size of alloc blk.
- ****************************************************************************/
-
-void mempool_multiple_fixed_free(FAR struct mempool_multiple_s *mpool,
-                                 FAR void *blk, size_t size);
-
 /****************************************************************************
  * Name: mempool_multiple_deinit
  *
diff --git a/mm/mempool/mempool_multiple.c b/mm/mempool/mempool_multiple.c
index ef799b7da3..b2233b3e24 100644
--- a/mm/mempool/mempool_multiple.c
+++ b/mm/mempool/mempool_multiple.c
@@ -406,101 +406,6 @@ void mempool_multiple_memdump(FAR struct mempool_multiple_s *mpool,
     }
 }
 
-/****************************************************************************
- * Name: mempool_multiple_fixed_alloc
- *
- * Description:
- *   Allocate an block from specific multiple memory pool.
- *   If the mempool of the corresponding size doesn't have free block,
- *   then wait until free happened or return NULL.
- *
- * Input Parameters:
- *   mpool - The handle of multiple memory pool to be used.
- *   size  - The size of alloc blk.
- *
- * Returned Value:
- *   The pointer to the allocated block on success; NULL on any failure.
- *
- ****************************************************************************/
-
-FAR void *mempool_multiple_fixed_alloc(FAR struct mempool_multiple_s *mpool,
-                                       size_t size)
-{
-  FAR struct mempool_s *pool;
-
-  pool = mempool_multiple_find(mpool, size);
-  if (pool == NULL)
-    {
-      return NULL;
-    }
-
-  return mempool_alloc(pool);
-}
-
-/****************************************************************************
- * Name: mempool_multiple_fixed_realloc
- *
- * Description:
- *   Change the size of the block memory pointed to by oldblk to size bytes.
- *
- * Input Parameters:
- *   mpool   - The handle of multiple memory pool to be used.
- *   oldblk  - The pointer to change the size of the block memory.
- *   oldsize - The size of block memory to oldblk.
- *   size    - The size of alloc blk.
- *
- * Returned Value:
- *   The pointer to the allocated block on success; NULL on any failure.
- *
- ****************************************************************************/
-
-FAR void *
-mempool_multiple_fixed_realloc(FAR struct mempool_multiple_s *mpool,
-                               FAR void *oldblk, size_t oldsize, size_t size)
-{
-  FAR void *blk;
-
-  if (size < 1)
-    {
-      mempool_multiple_fixed_free(mpool, oldblk, oldsize);
-      return NULL;
-    }
-
-  blk = mempool_multiple_fixed_alloc(mpool, size);
-  if (blk != NULL && oldblk != NULL)
-    {
-      memcpy(blk, oldblk, MIN(oldsize, size));
-      mempool_multiple_fixed_free(mpool, oldblk, oldsize);
-    }
-
-  return blk;
-}
-
-/****************************************************************************
- * Name: mempool_multiple_fixed_free
- *
- * Description:
- *   Release an memory block to the multiple mempry pool. The blk must have
- *   been returned by a previous call to mempool_multiple_fixed_alloc.
- *
- * Input Parameters:
- *   mpool - The handle of multiple memory pool to be used.
- *   blk   - The pointer of memory block.
- *   size  - The size of alloc blk.
- ****************************************************************************/
-
-void mempool_multiple_fixed_free(FAR struct mempool_multiple_s *mpool,
-                                 FAR void *blk, size_t size)
-{
-  FAR struct mempool_s *pool;
-
-  DEBUGASSERT(mpool != NULL && blk != NULL);
-
-  pool = mempool_multiple_find(mpool, size);
-  DEBUGASSERT(pool != NULL);
-  mempool_free(pool, blk);
-}
-
 /****************************************************************************
  * Name: mempool_multiple_deinit
  *