The Serum Type III Procollagen Peptides (SIIIPP) were determined in 35 individuals: 25 untreated schistosomotics: 16 with hepatointestinal (HI) and 9 with the compensated hepatosplenic (CHE) forms and a control group (C) consisted of 10 healthy volunteers. Kits of radioimmunoassay were performed for SIIIPP dosage. It was searched whether there was relationship between the SIIIPP and the serum levels of alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), alkaline phosphatase (AP) and gamma glutamyltranspeptidase (GGTP). The mean values of SIIIPP in the forms of HI (13.0 ng/ml) and CHE (17.0 ng/ml) were significantly higher than controls (9.0 ng/ml) (p less than 0.05). No significant difference was observed in SIIIP values between the HI and CHE patient groups, and between SIIIPP and ALAT, ASAT, AP and GGTP serum levels.