From February through December 1978, venereal disease casefinders in Polk County, Iowa used an expanded interview period of at least 120 days to interview 983 gonorrhea patients for sexual partner information. We grouped patients according to sex and clinical findings and evaluated the percentage of all new cases identified by time intervals within the expanded interview period. Ninety-one per cent of all untreated, infected sexual partners of symptomatic males were identified by using an interview period which spanned the interval from date of treatment to 15 days before symptom onset. In contrast, the traditional 30-day interview period missed 23 per cent of those untreated, infected partners named by women with pelvic inflammatory disease (PID), 34 per cent of those partners named by women with uncomplicated gonorrhea, and 29 per cent of those named by asymptomatic men. The Polk County data suggest the importance of basing interview periods upon a patient's sex and clinical presentation.