Our objective was to determine the optimal duration of treatment with imiquimod for external genital warts over 4, 8, 12 or 16 weeks. A total of 120 women with a history of genital warts for a median of 3-6 months and prior alternative treatments in 73% were evaluated for total clearance rates. There was no statistically significant difference in complete clearance rates after 16-week follow-up across treatment groups: four weeks (40.0%), eight weeks (48.4%), 12 weeks (39.3%) and 16 weeks (51.6%). Imiquimod was well tolerated, and in those treated for four weeks there was a lower incidence of local skin reactions such as erythema and erosion, and no incidences of pain. These preliminary results suggest that a four-week treatment course of imiquimod applied thrice weekly for women with external genital warts may provide a reasonable approach with comparable efficacy and compliance, and minimal adverse events, drug costs and clinic visits.