OBJECTIVE To test a sonoscopic technique developed for transvaginal catheterization and recanalization of the fallopian tube. DESIGN In a feasibility study, catheterization was performed with the use of laparoscopic control. Patients with bilateral proximal tubal obstruction underwent fallopian tube recanalization under ultrasonic observation. SETTING This study represents patients evaluated for primary or secondary infertility at Humboldt University Hospital. PATIENTS, PARTICIPANTS Proximal tubal obstruction had been diagnosed on previous hysterosalpingogram and with laparoscopy. INTERVENTIONS None. MAIN OUTCOME MEASURE Tubal patency was assessed by hydrotubation under ultrasonic observation. RESULTS Transvaginal catheterization was successful in 31 (91.2%) of the 34 tubes. In 19 patients with proximal tubal obstruction, patency of both or at least one tube was achieved in 16 (84.2%) women. Five (31.6%) of 16 patients successfully recanalized were found to have an intrauterine pregnancy at a 6-month follow-up interval. CONCLUSION This catheterization technique should be investigated for possible use in diagnostic schedule early in the evaluation of the infertile patient. Also, the transvaginal recanalization of proximally obstructed tubes calls into question the application of microsurgical treatment of a selected group of patients.