The aim of this study was to assess patient tolerance of two outpatient tests. Sixty-six infertile women were prospectively randomized to hysterosalpingo-contrast sonography (HyCoSy) (n = 34) or X-ray hysterosalpingography (HSG) (n = 32). The procedures were performed by the same operator. The uterine cavity outline and tubal patency were determined by both procedures. The mean times taken and the volume of contrast medium required for HyCoSy and HSG were similar: 12.1 +/- 5.2 and 9.5 +/- 4.8 min and 9.4 +/- 5.2 and 11.5 +/- 8.4 ml, respectively. Side-effects were assessed during the procedure, at 2 h, 24 h and 28 days. The most common side-effect was pelvic pain, in 56/66 (84%) women, occurring during the procedures (HyCoSy 19/34 (56%); HSG 23/32 (72/%)) and/or in the following 24 h (HyCoSy 14/34 (41%); HSG 15/32 (47%)). This was described as less severe or equal to their usual period pains (HyCoSy 100%; HSG 85%). Only 12/66 (18%) women required simple non-steroidal analgesia (HyCoSy 8/34 (24%); HSG 4/32 (13%)). There were no significant differences between the two methods concerning the frequency or severity of pains at different stages during and after the procedure or analgesia requirements. HyCoSy and HSG are equally well tolerated outpatient procedures for assessing tubal patency and uterine abnormalities. In addition, HyCoSy avoids the risks of ovarian irradiation and allows scanning of the uterine corpus and ovaries at the same time.