Riboflavine tetrabutyrate is a fat soluble riboflavine derivative. It was synthesized by esterification of riboflavine with fatty acid chloride or by esterification of riboflavine with fatty acid anbydride. The advantage of riboflavine tetrabutyrate is prolongation of its biologic half life and as a result enhancing effectivity of riboflavine, This riboflavine tetrabutyrate has been used for treatment of various dermatoses of which Pathogenesis are believed to be related with abnorma1 Iipid rnetabolism. Receatty, there were many case reports showing markedly improved clinical synptoms ofpsoriatic patients who had been administered oral riboflavine tetrabutyrate for more than one month in Japan. In this clinical trial, we have also experienced effectiveness in 4 of 7 psoriatic pztients who was given oral riboflavine t trabutyrate for more than 3 months.