ObjectiveTo assess the incidence of uterine cavity abnormalities diagnosed by office hysteroscopy in patients with normal hysterosalpingigram and transvaginal ultrasound; and the impact of office hysteroscopy on ICSI outcome.DesignProspective Cohort StudySettingThe In Vitro Fertilization Unit at Kasr Al Ainy University Hospital, Cairo, EgyptPatient(s)100 infertile patients scheduled for their first ICSI cycle will be included in the study. They will be further divided in to two groups; the intervention group which will undergo office hysteroscopy before ICSI and the control group.Intervention(s)All the participating patients will undergo ICSI; half of the patients will have office hysterosocopy as an additional procedure before undergoing ICSI.Main Outcome Measure(s)Undiagnosed uterine abnormalities and the pregnancy rate.ResultsThe results of this study were in concordance with previous other studies. The incidence of undiagnosed uterine abnormalities by HSG and TV/US was 48%. The pregnancy rate was even higher among the group of patients who had office hysteroscopy as a preliminary investigation before ICSI; 76% compared to the control group 54%. In addition tothe high specificity of office hysteroscopy in the diagnosis of uterine cavity abnormalities compared to HSG and TV/USConclusionOffice hysteroscopy should be implemented as a routine tool for investigating infertile patients, especially those undergoing ICSI.