Background: The TGFβ is a family of peptide growth factors that play an important role in regulating growth, differentiation and metabolism of many human cell types. It has previously been shown that TGFβ is measurable in human ovarian follicular fluid and that it is produced in both granulosa and theca cells in the human ovary. Investigating the factors responsible for growth and maturation of oocytes is important for evolution of in vitro maturation (IVM) of oocytes. Objective: The aim of this study was to determine the correlation between transforming growth factor present in follicular fluid on oocyte maturity. Setting: I.V.F center, Department of Obstetrics and Gynecology, Kasr El Aini Hospital, Cairo University. Material and methods: infertile patients undergoing ICSI and receiving long protocol for ovarian stimulation were included. At the day ovum pickup; follicular size was assessed by ultrasound before aspiration, then follicular fluid was aspirated and the level of TGF β1 was assessed and correlated with oocyte maturity and follicular size. The level of TGFβ1 in follicular fluid will be measured by Enzyme Linked Immunosorbent Assay (ELISA).