['To explore the possibility that local injury to the endometrium in controlled ovarian hyperstimulation cycle improves the incidence of embryo implantation and to analyze the gene expression profile in the endometria of pregnant and nonpregnant patients in in vitro fertilization/embryo transfer (IVF-ET).', 'Prospective study.', 'A clinical assisted reproductive center of a university hospital.', 'Women undergoing fresh IVF-ET cycles (n = 121), treated with a long protocol for controlled ovarian hyperstimulation, whose endometrium were diagnosed by B-ultrasound showing irregular echo.', 'Local injury to the endometrium of 60 patients in controlled ovarian hyperstimulation cycle, who were randomly selected from a total of 121 patients. Seven endometrial biopsies samples from day 10 were analyzed by Affymetrix U133 plus 2.0 gene chip.', 'Outcomes of IVF-ET and gene expression assayed by gene chip technology.', 'Transfer of the same number of embryos (135 in the experimental and control patients, respectively) resulted in rates of implantation (33.33% vs. 17.78%), clinical pregnancy (48.33% vs. 27.86%), and ongoing or live births per ET (41.67% vs. 22.96%) that were higher in the experimental group compared with controls. Statistically significant differences of the expression level of 218 genes (41 up-regulated and 177 down-regulated) were detected in the endometrial biopsy samples from clinical pregnant patients and nonpregnant patients.'] Does local injury to the endometrium in controlled ovarian hyperstimulation cycles improve implantation rates?