Medical Massive Open Online Courses (MOOCs) have been integrated into formal campus teaching by several universities. However, teaching attributes of medical MOOCs have not been systematically investigated. Additionally, guidelines are needed to inform integration practices. This study systematically investigated the available teaching modes and social-epistemological dimensions of medical MOOCs. An overview of MOOCs on a medical topic was compiled and inclusion criteria were developed. A data collection tool was composed and calibrated. For data collection, out of 410 MOOCs 33 were selected based on these criteria. Investigators enrolled in selected MOOCs and analyzed teaching modes after examination of all course pages. Teaching modes were categorized in social-epistemological dimensions according to the Teaching Approach Framework. Twenty-nine different teaching modes were found, showing wide distributions. Analysis of social-epistemological dimensions showed medical MOOCs focus on constructivist and individual teaching modes as opposed to objectivist and group modes. Medical MOOCs do not have a universal teaching mode profile. They contain a rich variety of teaching modes for integration in campus education of which videos, discussion boards, and multiple choice questions are used regularly. Constructivist teaching modes are readily available in medical MOOCs and can support educational innovation of formal campus teaching when integrated.