Objective of study was to determine whether ovarian follicular fluid stem cell factor concentrations are important for oocytes maturity and associated with successful IVF pregnancies. Design: Cohort design study of 30 women with infertility at which evaluation of stem cell factor levels from the follicular fluid at the time of oocyte retrieval undergone after controlled ovarian hyperstimulation. Setting: IVF centre of Kasr El Ainy Hospital. Patients: 30 Infertile women undergoing ICSI in IVF centre of Kasr El Ainy Hospital. The follicular fluid aspirated from 96 follicles of 30 women undergoing ICSI for tubal factor or unexplained infertility was assessed for SCF by ELIZA. Only clear follicular fluid aspirated was assessed for SCF and its level was correlated with oocyte maturity. Also, SCF level was correlated to pregnancy outcome. Main outcome measures: Follicular fluid stem cell factor concentration and pregnancy. Results: Stem cell factor concentrations were significantly higher in the mature follicles than in immature follicles (22.16±5.9 versus 8.6±4.7 ng/ml), p value = 0.000 and the stem cell factor concentrations were significantly higher in follicular fluid of the patients who achieved successful pregnancies than in those who did not (24.7±3.5 versus 18.1±4 ng/ml), p value = 0.000. Conclusion: Elevated follicular fluid stem cell factor concentrations are associated with an increased likelihood of maturity of the ovarian follicles and ICSI success. Therefore, stem cell factor may play a role in human follicular and oocyte development, and might have a role in invitro maturation.