A pattern of genital injury that separates trauma seen in sexual assault cases from trauma seen following consensual sexual intercourse has been a matter of debate. This study aimed at clarifying the question by eliminating as many confounders as possible in a prospective, case-control setup. A total of 98 controls and 39 cases were examined using the naked eye, the colposcope and toluidine blue dye followed by colposcopy. The overall frequency of having at least one lesion was strikingly similar in the two groups, but cases had significantly more abrasions, a trend towards more haematomas and a higher frequency of multiple lesions. Cases had a higher frequency of lesions in locations other than the 6 o'clock position. Our data suggests that cases have larger, more complex lesions. In conclusion, this study has confirmed the existence of different patterns of genital lesions. Background data for detection of genital lesions using the three most commonly used techniques is provided. These results will aid in the interpretation of findings seen when examining sexual assault victims.