They present results for lens-free microscopy for the imaging of dense cell culture. With this aim, they use a multiwavelength LED illumination with well separated wavelengths, together with the implementation of an appropriate holographic reconstruction algorithm. This allows for a fast and efficient reconstruction of the phase image of densely packed cells (up to 700 cells/mm2) over a large field of view of 29.4 mm2. Combined with the compactness of the system which fits altogether inside an incubator, lens-free microscopy becomes a unique tool to monitor cell cultures over several days. The high contrast phase shift images provide robust cell segmentation and tracking, and enable high throughput monitoring of individual cell dimensions, dry mass, and motility. They tested the multiwavelength lens-free video-microscope over a broad range of cell lines, including mesenchymal, endothelial, and epithelial cells. © 2017 International Society for Advancement of Cytometry. © 2017 International Society for Advancement of Cytometry