Described herein are methods and systems for analyzing a sample by applying time resolved laser induced fluorescence spectroscopy to the sample to measure lifetime time decay profile data relating to the sample, and applying multivariate analysis to process the data so as to classify a sample as, for example, normal or abnormal. The sample may be cells, fluid or tissue from any organ. The sample may be in vitro or in vivo. The data may be obtained in situ or in vitro.