Objectives: The purpose of this study is to investigate the effects of monocryl (Polyglecaprone 25), silk and catgut suture materials on wound healing in diabetic rats and to evaluate NO (nitric oxide) dynamics. Study desing: Fourty-eight male Wistar-Albino rats weighting 220-270 g were used in this study. The rats were categorized into 2 groups, as control group (n=24) and streptozotocin (STZ) induced diabetic group (n=24). For each group, incision wounds were created on the inner cheeck mucosa of the animals and wounds were closed primarily with three different types of sutures. These materials were sized 3-0 monocryl (polyglecaprone 25), silk and catgut sutures swaged on. Excisional biopsies were performed at 2nd, 7th, 14th and 21st day (2 rats per day) from the initial surgical procedure. Effects of these suture materials on wound healing and NOS (nitric oxide synthase) activities were compared immunohistochemically in the study. eNOS and iNOS (Endothelial and induced nitric oxide synthase) activities were classified as mild (+), moderate (++) and severe (+++). Results: Mild eNOS activities were seen in both diabetic and control groups at 2nd day specimens. Activities of silk and catgut were similar both in diabetic and control groups at 14th day, this activity in monocryl was mild. 21st day specimens revealed that monocryl has mild eNOS activity than silk and catgut sutures. iNOS activities in diabetic group were greater than control groups and the degrees of the activity in monocryl, silk and catgut sutures were mild, severe and moderate at the 7th day. At the 14th day there was no iNOS activity in diabetic monocryl group. Conclusion: All of the materials have the potential capacity to be well tolerated however monocryl seemed to have more benefical effects on wound healing in diabetic subjects.