AIM & HYPOTHESIS: Resolvins, derived from omega-3 fatty acids, may actively resolve inflammation. Resolvin E1 (RvE1) binds to Chem-R23 as an endogenous anti-inflammatory and pro-resolving lipid mediator. We hypothesized that RvE1 may also activate osteoblasts to restore critical size bone defects in a calvarial model. MATERIALS & METHODS: An in-vitro calvarial culture system was used to evaluate the stimulative effects of RvE1 compared to Amniotic Growth Factor (AGF) (a known stimulant in this system) on critical size defects under static conditions. Calvaria harvested from 10 mice and separated into 20 calvaria halves were cultured under conditions favoring bone formation. The test groups were defect only, defect plus a collagen membrane, defect plus a collagen membrane plus RvE1, and defect plus a collagen membrane plus AGF. The effect of RvE1 and AGF on healing of a critical size bone defect was assessed with both histological evaluation and alkaline phosphatase assays. RESULTS: RvE1 binds in a receptor-ligand interaction with Chem-R23 in the periosteum to stimulate cellular proliferation and migration into a critical size bone defect of neonatal mouse calvaria. CONCLUSION: These results suggest that RvE1 has a direct effect on osteoblast activity at and around the edge of a critical size 2 mm defect without an inflammatory reaction.