The histochemical detection of androgen and estrogen receptors in human prostatic tissue was achieved employing fluorescein labeled conjugates of bovine serum albumin linked to testosterone and estradiol. Results were compared to those of dextran-coated charcoal and protamine sulfate assays and correlated in 85% of specimens. Early findings include a relatively uniform distribution of receptor in hyperplastic epithelium in contrast to marked tumor cell receptor heterogeneity in cancer. Location of receptor in nucleus and/or cytoplasm was readily determined.