SEVEN ADULT MALE VOLUNTEERS, TWO OF WHOM WERE CIRCUMCISED, PROVIDED THE PENILE WASHINGS USED IN THIS STUDY. A TOTAL OF 20 SPECIMENS WAS OBTAINED. THE PROCESS FOR THE COLLECTION OF SPECIMENS AND THE STAINING TECHNIQUES ARE DESCRIBED. THIS PROCEDURE YIELDED UNIFORMLY EXCELLENT RESULTS. THE STUDY WAS THEN EXPANDED TO SEE HOW THESE RESULTS COULD BE APPLIED TO FORENSIC SCIENCES. CELLS FROM THE GLANS PENIS, URINE, SEMEN, AND VAGINA WERE FOUND IN THESE WASHINGS. ONE OF THE MOST CRITICAL ASPECTS OF THIS PROCEDURE IS DETERMINING THE SEX OF THE PERSON FROM WHOM THE CELLS CAME BY CYTOLOGIC EXAMINATION OF SEX-CHROMATIN BODIES. PROCEDURES FOR DETERMINING THE SEX ARE OUTLINED. THE DURATION OF EVIDENCE IS VARIABLE, SO THE EFFECT OF TIME ON THIS PROCEDURE IS NOT KNOWN. HOWEVER, BATHING WILL REMOVE ALL EVIDENCE, AND A CURSORY WASHING WILL OFTEN LEAVE SOME VAGINAL CELLS IN THE FRENULUM. AT THE TIME OF THIS STUDY, THERE WAS NO METHOD OF ESTABLISHING A CONNECTION BETWEEN THE CELLS FOUND BY THIS PROCEDURE AND AN ALLEGED VICTIM, BUT VARIOUS CYTOLOGIC CHARACTERISTICS HAVE POTENTIAL FOR GROUPING THE DONORS IN CERTAIN BROAD CATEGORIES THAT MIGHT BE OF EVIDENTIARY VALUE. THIS TECHNIQUE IS ONLY A POSSIBLE AID IN THE DETERMINATION OF RECENT COITUS IN THE SUBJECT AS IT CANNOT DIFFERENTIATE INTERCOURSE FROM RAPE. MORE STUDY IS NECESSARY TO ANALYZE THE IMPLICATIONS AND POSSIBLE USES OF THESE DATA. REFERENCES ARE PROVIDED. (BAC)