Image segmentation is a process of dividing an image into multiple coherent regions. Segmentation of biomedical images can assist diagnosis and decision making. Manual segmentation is time consuming and requires expert knowledge. One solution is to segment medical images by using deep neural networks, but traditional supervised approaches need a large amount of manually segmented training data. A possible solution for the above issues is unsupervised medical image segmentation using deep neural networks, which our work tries to solve with our proposed 3D Attention W-Net.