Objective: To evaluate the biochemical and histopathological effects of diclofenac and ketoprofen administration on bone regeneration in a calvarial defect model in rats. Material and Methods: The sample consisted of 108 Wistar rats that were randomly distributed in three groups, to which an osteotomy of 6 mm in diameter was performed in the calvaria. Group A (control) was given saline solution; Group B received ketoprofen 2 mg/kg and Group C received diclofenac 2 mg/kg. All treatments were administered intraperitoneally every 12 hours for 3 days. Bone regeneration was evaluated by biochemical (alkaline phosphatase and serum calcium) and histopathological (osteocyte and osteoblast cell count) characteristics at 15 and 30 days. Results: In the biochemical evaluation, alkaline phosphatase levels in the ketoprofen group were significantly lower compared to the diclofenac group at 15 and 30 days (p= 0.015 and p= 0.001; respectively). However, serum calcium levels did not show the difference between the study groups at 15 and 30 days (p= 0.42 and p= 0.81; respectively). In the histopathological analysis, the count of osteoblasts and osteocytes was significantly lower in the ketoprofen group compared to the diclofenac group at 15 and 30 days (p< 0.05). Conclusion: The administration of ketoprofen has negative biochemical and histopathological effects of greater intensity on bone regeneration compared to the administration of diclofenac.