Infection can be a trigger or an aggravating factor in psoriasis, and in particular, bacterial focal infection is well documented to exacerbate psoriasis presumably through its superantigen. Since fungi could produce superantigen as well, and periungual involvement is often seen in psoriatic patients, we examined if local Candida infection plays some pathogenetic role or not in periungual lesions. In 15 psoriatic patients with periungual involvement, Candida infection was examined by microscopic study, culture, and antifungal treatment. We found no evidence suggestive of the relationship between Candida and psoriatic changes in periungual area.