19 patients with plaque-style mycosis fungoides have undergone determination of HLA antigen distribution. Deviations from the expected distribution frequency occurred with the antigens of the W19 group comprising A29, W30, W31 and W32 and of B8 and Al. The W19 group deviation was statistically significant (χ2 = 9.7 p value < 0.005). The significance of this observation in relation to reported immunological abnormalities in mycosis fungoides is discussed