Mycophenolic acid is an antimetabolite used experimentally for the treatment of psoriasis. Thirty-eight patients were treated with mycophenolic acid. A double-blind, placebo-controlled study demonstrated the efficacy of mycophenolic acid (P less than .01). A long-term safety study showed the occurrence of hematologic abnormalities, viral infections, and carcinoma. The position of mycophenolic acid in the therapeutic treatment of psoriasis must await the results of a multicenter cooperative study.