In 1998, transvaginal hydrolaparoscopy (THL) was introduced as a new outpatient procedure for exploration of tubo-ovarian structures and tubal patency in subfertile patients. At present, there are no large studies that relate the findings at THL to fertility outcome. Consecutive patients undergoing THL for subfertility between 2000 and 2004 were included in this prospective cohort study. Follow-up ended when ongoing pregnancy or tubal surgery occurred or at the day of last contact. Kaplan-Meier curves for the occurrence of intrauterine pregnancy (IUP) (spontaneous or after intrauterine insemination) were constructed for a normal THL, a THL with a one-sided tubal pathology and a THL with a two-sided tubal pathology. Fecundity rate ratios (FRRs) were calculated to express the association between THL findings and the occurrence of IUP. Patients rated their pain experiences and acceptability on a visual analogue scale (VAS). We included 272 women. In 96% (261) of the patients, access to the pouch of Douglas was achieved. Complications occurred in 2% of the procedures. In 203 (78%) patients, both tubo-ovarian structures could be visualized and tubal patency was shown. One-sided tubal occlusion was found in 10%, whereas two-sided tubal occlusion was seen in 4% of the patients. Adhesions and/or endometriosis were observed in 8% of the patients. The FRRs for one-sided tubal pathology, two-sided tubal pathology and adhesions/endometriosis were 0.59, 0 and 0.80, respectively. The VAS scores showed pain to be limited and the procedure to be acceptable. THL is a feasible technique. Its capacity to predict spontaneous ongoing pregnancy is comparable to that of laparoscopy.