Purpose: To determine if an injection of granulocyte colony stimulating factor (G-CSF) prevoulatory can enable oocyte release from the follicle in women who have failed to release in natural cycles despite an endogenous luteinizing hormone (LH) surge, and also despite treatment with human chorionic gonadotropin (hCG) or a gonadotropin releasing hormone agonist (GnRHa). Materials and Methods: A single injection of 100 mg G-CSF was given in the late follicular phase followed by hCG 10,000 units at peak follicular maturation in women with at least three consecutive cycles of luteinization without oocyte release. Results: Six women had ten cycles with G-CSF and hCG. Definite release occurred in four, inconclusive in four, and definitely the luteinized unruptured follicle in two. Biochemical pregnancies occurred in two of the cycles where oocyte release occurred and a live delivered pregnancy in another cycle of release. Conclusions: Without controls one cannot state with certainty that G-CSF enabled oocyte release when hCG and leuprolide failed. Nevertheless, the data do support a trial with G-CSF before proceeding to IVF-ET.