Epidermal growth factor (EGF) is a mitogen that stimulates cell division of various cells of epidermal origin. The present study was undertaken to clarify whether the serum level of EGF is correlated with the disease activity during local therapy with dithranol in psoriasis. We examined serum EGF concentrations in acute and chronic psoriasis before and after topical treatment with dithranol and the correlation with Psoriasis Activity and Severity Index (PASI). Male patients were divided into two groups: acute psoriasis (AP, 18 cases) and chronic psoriasis (CP, 17 cases). A control group C consisted of 20 healthy male volunteers. Radioimmunoassay of EGF was performed using the reagent pack (Amersham, UK). In the CP group mean EGF was higher before treatment than in the AP and C groups, but not significantly. EGF concentration after local treatment was higher in the CP group than the AP group (P < 0.02); the AP group, however, showed statistically significant decrease of EGF after the treatment (P < 0.04). No correlation between EGF and PASI was found. Serum EGF concentration increased in 19/35 treated patients.