Cell proliferation can be efficiently analyzed by multiparameter flow cytometry. Different strategies may be used: As a primary approach, static analysis reveals the momentary distribution in a single sample between cell cycle phases, metabolic states, or differentiation lineages. Kinetic analysis uses sequential measurements of cell cycle traverse in synchronized cell populations or accumulation of cells blocked in a particular cell cycle phase. DNA replication analysis is based on the incorporation of the thymidine analogue bromodeoxyuridine. Cell production by mitosis as well as cell loss by cell death can be estimated. Cell production may be assessed by measurement of mitotic rate or S-phase influx. Cycling/non-cycling status may be indicated by proliferation associated antigens. Specific cell clones in experimentally mixed populations can be discriminated using reporter genes. Flow cytometric multiparameter analysis has the potential of revealing and quantitating the heterogeneity with respect to stemlines, proliferation and differentiation. This is of increasing importance in the study of human cancers, as a possible basis for therapeutic decision making.