To clarify the role of chymase produced by mast cells in adhesion formation, we investigated the preventive effect of a specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)2, on adhesion formation in a hamster experimental model. Hamsters underwent resection of the right uterine body and then 10 microM Suc-Val-Pro-Phe(p) (OPh)2 or placebo was injected into the abdomen. Two weeks after the operation, the scores for adhesion formation in the chymase inhibitor-treated group were significantly lower than that in the placebo-treated group (placebo-treated group, 3.60+/-0.22; chymase inhibitor-treated group, 2.10+/-0.22; P<0.01). This specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)2, significantly suppressed the scores for adhesion formation in a hamster experimental model. Thus, chymase may play an important role in the adhesion formation.