diff --git a/assets/scripts/train.sh b/assets/scripts/train.sh
index ea74d99..4d00770 100755
--- a/assets/scripts/train.sh
+++ b/assets/scripts/train.sh
@@ -31,6 +31,7 @@ CUDA_VISIBLE_DEVICES=0 mpirun -n 1 python entry.py train \
             MODEL.DECODER.SPATIAL.ENABLED True \
             MODEL.DECODER.GROUNDING.ENABLED True \
             LOADER.SAMPLE_PROB prop \
+            BioMed.INPUT.RANDOM_ROTATE True \
             FIND_UNUSED_PARAMETERS True \
             ATTENTION_ARCH.SPATIAL_MEMORIES 32 \
             MODEL.DECODER.SPATIAL.MAX_ITER 0 \
diff --git a/configs/biomed_seg_lang_v1.yaml b/configs/biomed_seg_lang_v1.yaml
index 5d1fb78..f790fb4 100755
--- a/configs/biomed_seg_lang_v1.yaml
+++ b/configs/biomed_seg_lang_v1.yaml
@@ -289,6 +289,7 @@ BioMed:
     COLOR_AUG_SSD: False
     SIZE_DIVISIBILITY: 32
     RANDOM_FLIP: "none"
+    RANDOM_ROTATE: False
     MASK_FORMAT: "polygon"
     MIN_AREA: 30
     FORMAT: "RGB"
diff --git a/datasets/dataset_mappers/biomed_dataset_mapper.py b/datasets/dataset_mappers/biomed_dataset_mapper.py
index 36b4d44..9f101cc 100755
--- a/datasets/dataset_mappers/biomed_dataset_mapper.py
+++ b/datasets/dataset_mappers/biomed_dataset_mapper.py
@@ -121,6 +121,7 @@ def __init__(
         max_token_num,
         tokenizer,
         binary_classes: bool,
+        rotate: bool,
     ):
         """
         NOTE: this interface is experimental.
@@ -153,6 +154,7 @@ def __init__(
         self.max_token_num = max_token_num
 
         self.binary_classes = binary_classes
+        self.rotate = rotate
 
     @classmethod
     def from_config(cls, cfg, is_train=True):
@@ -188,7 +190,8 @@ def from_config(cls, cfg, is_train=True):
             "retrieval": retrieval,
             "max_token_num": max_token_num,
             "tokenizer": tokenizer,
-            "binary_classes": cfg['MODEL']['ENCODER']['BINARY_CLASSES']
+            "binary_classes": cfg['MODEL']['ENCODER']['BINARY_CLASSES'],
+            "rotate": cfg['INPUT']['RANDOM_ROTATE'],
         }
         return ret
 
@@ -213,6 +216,12 @@ def __call__(self, dataset_dict):
         image, transforms = T.apply_transform_gens(self.tfm_gens, image)
         image_shape = image.shape[:2]  # h, w
 
+        rotate_time = 0
+        if self.is_train and self.rotate and random.random() < 0.5:
+            rotate_time = random.randint(1, 3)
+        if rotate_time > 0:
+            image = np.rot90(image, rotate_time)
+
         # Pytorch's dataloader is efficient on torch.Tensor due to shared-memory,
         # but not efficient on large generic data structures due to the use of pickle & mp.Queue.
         # Therefore it's important to use torch.Tensor.
@@ -252,6 +261,8 @@ def __call__(self, dataset_dict):
                 m = 1 * (m > 0)
             m = m.astype(np.uint8)  # convert to np.uint8
             m = transforms.apply_segmentation(255*m[:,:,None])[:,:,0]
+            if rotate_time > 0:
+                m = np.rot90(m, rotate_time)
             masks_grd += [m]
             rand_id = random.randint(0, len(ann['sentences'])-1)
             texts_grd.append(ann['sentences'][rand_id]['raw'].lower())
@@ -320,6 +331,8 @@ def __call__(self, dataset_dict):
 
                     m = m.astype(np.uint8)  # convert to np.uint8
                     m = transforms.apply_segmentation(m[:,:,None])[:,:,0]
+                    if rotate_time > 0:
+                        m = np.rot90(m, rotate_time)
                     masks_grd += [m]
                     # random select a sentence of a single annotation.
                     rand_index = random.randint(0, len(ann['sentences'])-1)