Study question : Is plasma level of reactive oxygen speciesaffected by antioxidants pretreatment in endometriotic women?Summary answer: plasma concentrations of ROS are reducedby pretreatment with antioxidants before ICSI procedure inendometriotic women.Study design, size, duration: prospective randomizedcontrolled clinical trial , 50 patients with endometriosisdiagnosed by US prepared for ICSI were enrolled in the studyafter consent. They were randomized into 2 groups, 25 receivedantioxidants before starting the protocol , 25 did not receive ,randomization was done by closed envelop single blind forpatients.Materials and methods: was done in the Egyptian IVF centre ,all patients were subjected to plasma samples before start longprotocol for induction and second on day of ovum pick up,embryo transfer was done according to embryo grading .Main results and the role of chance: ROS were significantlyreduced in patients received antioxidants compared to the othergroup ,no statistically significant increase in success rate ofICSI.Limitations, reasons for caution: low number of participants ,low number of endometriotic women.