A method for registration of images of tissue slices comprises: receiving a first image (18a) of a first tissue slice (14a) and a second image (18b) of a second tissue slice (14b), both tissue slices being prepared from the same tissue block (10); determining an unreliable area (27) in the first image (14a) showing folded tissue (15); and registering the first image (14a) and the second image by registering an area of the first image and the second image outside of the unreliable area.