To evaluate the effect of ibuprofen (Motrin) on the development of neointimal fibrous hyperplasia (NFH), 4 cm segments of expanded polytetrafluoroethylene (ePTFE) grafts with an internal diameter of 4 mm were implanted in the femoral arteries of 28 dogs. Three dogs served as controls and these grafts were removed at 7 to 14 days. The remaining 25 dogs were medicated with either intravenous (IV) or oral (PO) ibuprofen. The medicated dogs were grouped according to whether the ibuprofen was administered prior to or after graft implantation. The orally medicated dogs were also grouped according to whether the grafts were removed from 30 to 60 days after graft implantation. The grafts were analyzed for the amount of anastomotic initimal hyperplasia, pannus extension, thrombus deposition, and patency. Analysis of the data demonstrated no statistically significant differences among any of the treatment groups or the control group for the variables analyzed. We conclude that ibuprofen neither prevents nor retards the development of NFH. There was a trend toward less thrombus deposition in the animals that received oral ibuprofen preoperatively. There was also a trend toward higher patency in the animals that received ibuprofen prior to graft implantation, which most likely resulted from decreased thrombus and fibrin deposition.