To compare the safety and efficacy of the transobturator tape (Monarc) with the retropubic tape (tension-free vaginal tape, TVTR) for the treatment of urodynamic stress incontinence (USI) a prospective, single-blinded, multi-centre randomised clinical controlled trial was undertaken in four urogynaecology units in Australia. One hundred and eighty-seven women with USI were randomly allocated to undergo surgery with either the Monarc sling (n = 80) or TVT (n = 107). Outcome measures were intra-operative complications (especially bladder injury), as well as peri-operative complications, symptomatology, quality of life and urodynamic outcomes. At 3 months, data were available on 140 women, 82 (59%) TVT and 58 (42%) Monarc. The TVT group was significantly more likely to be complicated by bladder injury (7 TVT, 0 Monarc, p < 0.05). Blood loss and operative time were significantly less in the Monarc group, which was 49 mls (31) vs that of the TVT group, which was 64 mls (41) p < 0.05; 18.5 min (6.5) TVT vs 14.6 min (6) Monarc (p < 0.001). The subjective and objective stress incontinence cure rates were 86.6% (71) vs 72.4% (42) p = 0.77 and 79.3 vs 84.5%, p = 0.51 for the TVT and Monarc groups, respectively. Both groups reported similar improvement in incontinence impact and satisfaction with their operation, although return to activity was significantly quicker with the transobturator route (p = 0.029). The transobturator tape appears to be as effective as the retro-pubic tape in the short term, with a reduction in the risk of intra-operative bladder injury, shorter operating time, decreased blood loss, and quicker return to usual activities.