The composition of free fatty acids of hair lipids from subjects with psoriasis vulgaris (n = 60) and a control group (n = 30) was determine by gas liquid chromatography. The analysis indicates that the percentage composition of longer chain fatty acids was distinctly higher in psoriasis vulgaris. It is suggested that patients with psoriasis vulgaris have either a different air lipid composition and a different microbial activity or different activities of the epidermic esterases.