Abstract: A method for a microscope-based quantitative analysis of contact-dependent cell-to-cell transfer between cells. Single donor cells containing a traceable marker are cultured in a lawn of acceptor cells to allow cell-to-cell transfers. The donor and acceptor cells are then imaged and/or stained for microscopy to determine the location, shape and volumes of donor cells and of surrounding acceptor cells within selected regions of interest. The spatial distribution of the traceable marker in each volumetric picture element of the region of interest is determined and analyzed to determine quantitatively and qualitatively the substance transfer. The method allows a reliable quantitative evaluation of the effect of an active agent on cell-to-cell molecular communication and disease transmission.