The evidentiary exam following sexual assault provides crucial evidence that can be used by the prosecuting attorney to obtain a conviction in sexual assault cases. Evidence is collected for three purposes: to corroborate the use of force; to corroborate that recent sexual contact occurred; and to identify the perpetrator. Relatively few assailants (4%) go to jail for rape. To a great extent this is because of a lack of corroborating evidence and misinterpretation of this lack of evidence by police, courts, and jurors. This paper presents the results of a study to determine the likelihood of obtaining corroborating evidence of recent coitus along with an explanation of what negative results mean. Based on the results, recommendations are presented for sexual assault evidence collection in emergency departments.