The 2015 workshop on medical computer vision (MCV): algorithms for big data took place in Munich, Germany, in connection with MICCAI (Medical Image Computing for Computer Assisted Intervention). It is the fifth MICCAI MCV workshop after those held in 2010, 2012, 2013 and 2014 with another edition held at CVPR 2012 previously. This workshop aims at exploring the use of modern computer vision technology in tasks such as automatic segmentation and registration, localisation of anatomical features and extraction of meaningful visual features. It emphasises questions of harvesting, organising and learning from large-scale medical imaging data sets and general-purpose automatic understanding of medical images. The workshop is especially interested in modern, scalable and efficient algorithms that generalise well to previously unseen images. The strong participation in the workshop of over 80 persons shows the importance of and interest in Medical Computer Vision. This overview article describes the papers presented at the workshop as either oral presentations or posters. It also describes the three invited talks that received much attention and a very positive feedback and the general discussions that took place during workshop.