the MEDIA MICCAI special issue 2021 The 24th Medical Image Computing and Computer Assisted Interventions (MICCAI) conference, initially planned in Strasbourg, France, was held from September 27th to October 1st on a virtual platform. In spite of its unconventional nature, the virtual conference attracted over 2500 world-leading scientists from the fields of medical image segmentation, machine/deep learning, registration, computer-aided diagnosis, and computer assisted interventions, applied on various types of medical images ranging from MRI, CT, microscopic, ophthalmic, and ultrasound imaging. We received a total of 1630 submissions, and after a thorough double-blind peer-review process involving 1220 reviewers and 96 area chairs, 531 papers were finally accepted and presented at the conference.