Fluorescence lifetime imaging microscopy (FLIM) is a technique that has shown the ability to differentiate malignant from benign tissue in vivo and ex vivo. However, the complexity, long duration and effort required to generate this information has limited the adoption of these techniques in a clinical setting. Our group has developed a time-resolved imaging system that does not require the extraction of lifetimes or use of complex curve fitting algorithms to display the needed information. The technique converts fluorescence lifetime decay information directly into visual contrast by a normalization method. Numerous human tissues has been imaged, including head and neck squamous cell carcinoma and brain cancer biopsy specimens. This method is capable of providing both anatomical and chemical information for the pathologist and the surgeon. These results suggest that this technology has a possible role in identifying tumors in tissue specimens and detecting tumor margins during procedures.