Objective: To compare the diagnostic accuracy, pain scores, and procedure length of outpatient hysteroscopy (OHS), hysterosalpingography (HSG), and saline infusion hysterosonography (SIS) for evaluation of the uterine cavity of infertile women. Design: Prospective, randomized, investigator-blind study. Setting: Tertiary infertility clinic. Patient(s): Forty-six consecutive infertile women. Intervention(s): Outpatient HSG, OHS, and SIS, followed by operative hysteroscopy (HS). Main Outcome Measure(s): Uterine abnormalities, procedure length, and subjective pain. Result(s): Fifty-nine percent of infertile subjects were found to have an abnormality on at least one of three outpatient uterine evaluations. When compared with the case of definitive operative HS, 60% of abnormalities were correctly classified by HSG, 72% by OHS, and 52% by SIS (P: NS). When comparing all combinations of 2 outpatient screening tests to operative hysteroscopy, 68% were correctly classified by HSG/OHS, 58% by HSG/SIS, and 64% by OHS/SIS (P: NS). The average time length for the OHS was 9.1 min., which was significantly greater than for both HSG (average, 5.3 min) and SIS (average, 6.1 min.) (P<.0001 for both). HSG and SIS were not statistically different regarding procedure time length. The average pain score (0-10) for SIS was 2.7, compared with 5.8 and 5.3 for HSG and OHS, respectively. Both HSG and OHS mean pain scores were significantly greater than the SIS mean. Conclusion(s): OHS, SIS, and HSG were statistically equivalent regarding evaluation of uterine cavity pathology in infertile women. (Fertil Steril(R) 2000;74:1029-34. (C) 2000 by American Society for Reproductive Medicine.).