Although perianal Bowen's disease (BD) is a relatively uncommon malignancy, it is being detected with increasing frequency. It has a strong tendency for local recurrence and treatment remains controversial. The effectiveness of different treatment modalities, ranging from aggressive wide local excision with skin grafting to the application of a topical immune response modifier, remains uncertain. To our knowledge only two cases of perianal BD, successfully treated with imiquimod, have been reported. We wish to present the third case, effectively treated with imiquimod.