Androgen receptor (AR) plays an important role in growth and hormonal therapy of human prostate tumors. Immunohistochemical analysis of AR expression, a nonquantitative technique, is currently used for screening of receptor expression in prostate tissues. The present report describes a laser flow cytometric method for monitoring AR expression in human cell lines and in archival formalin-fixed paraffin-embedded prostate tissues and tumors. Multiparametric flow analysis can be used for simultaneous detection of other cellular markers (e.g., DNA aneuploidy), and by gated analysis, AR expression in subpopulations of a tumor can be quantitatively determined.