MeVisLab is a visual programming and rapid prototyping platform for image processing research and development with a focus on medical imaging. MeVisLab provides a flexible and simple handling of visualization and image processing algorithms by modular visual programming. No programming knowledge is required to set up image processing and visualization pipelines. Complete applications including user interfaces can easily be built within a general framework. Beside general image processing and visualization tools, MeVisLab includes advanced medical imaging algorithms for segmentation, registration, and quantitative morphological and functional analysis. Best of all, MeVisLab is now also available on Mac OS X – free for non-commercial use.