Abstract: The values of 6-Keto-Prostaglandin F_1α (6-K-PGF_1α),cAMP and cGMP in plasma from 39 patients with psoriasis vulgaris and normal persons were assayed.The results showed that the mean value of 6-K-PGF_1α from patients was 114.26±23.19pg/ml and that of cAMP was 14.71±3.82 pmol/ml.In comparison with normal persons,the difference was very significant (P <0.01).The mean value of cGMP of the patients was 8.20±1.54pmoI/ml,signif candy higher than that of normal persons (P <0.01).The ratio of cAMP/cGMP for normsl persons and patients was 3.06/1.79 (P<0.01).By linear correlation and regresson analyses,6-K-PGF_1α was found to be positive correlation with cAMP (r=0.498 P<0.01) and negative correlation with cGMP (r=-0.358,0.011α,cAMP and cGMP in psoriasis are discussed in this article.