Objective: 1) To investigate the relationship between operator experience and the success of outpatient hysteroscopy; and 2) to determine if the introduction of normal saline and the use of narrow-caliber hysteroscopes and vaginoscopic approach are associated with a lower failure rate. Design: Retrospective study. Setting: Teaching-hospital based outpatient hysteroscopy clinic. Patient(s): Five thousand consecutive women undergoing outpatient hysteroscopy between October 1988 and June 2003. Intervention(S): The hysteroscopies were carried out both by experienced.-operators and by trainees. Procedures were performed using 4-mm and 2.9-mm telescopes with 5-mm and 15-min diagnostic sheaths, respectively. Between October 1988 and 1996, the uterine cavity was distended with CO2 (CO2 period), whereas normal saline was hysteroscope insertion and vaginoscopic preferred after 1997 (1997-2003: saline period). Traditional technique of approach were used depending on operator preference and experience and pa ti, e ntcharactenstics. Main Outcome Measure(s): Success, failure, and complication rates. p Y, opera ReStilt(S): The hysteroscopies were successfully performed inneaity 5%,6f,,,ca;-b -36-2, tors (mean 13.8 ''d Hp 'ere 5.2% ga, offfate w, o and 5.4% I hysteroscopies per operator) with different levels of expertise. Failure an com I -and- saline p6f W9 MiIiijhpita6ks and shoulder respectively, without any significant difference between C02 hyWt8r6 660, was negatively afpain were significantly higher during the C02 period. The success ofloutpatieriv fected by postmenopausal status, nulliparity, need for cervical dilatation technique of hysteroscope insertion, and use of a 5-min hysteroscope. Conclusion(s): A high level of expertise is not a prerequisite to perforriting-hy'ste'rid'scopy on an outpatient basis. I Recent advances in technique and instrumentation facilitate this approach and might encourage greater adoption by the wider gynecology community. (Fertil SterilQD 2008;89:438-43. @2008 by American Society for Reproductive Medicine.)