Thermal ablation of the endometrial lining of the uterus is a minimally-invasive technique for treatment of menorrhagia. We have previously presented a 915 MHz microwave triangular loop antenna for endometrial ablation. Uterine fibroids are benign pelvic tumors, of considerably different water content compared to normal uterus, and may change the shape of the uterus. Collectively, these changes introduced by fibroids may alter the pattern of microwave endometrial ablation. In this study, we have investigated the effect of 1 - 3 cm diameter uterine fibroids in different locations around the uterine cavity on ablation profiles following 60 W, 150 s microwave exposure with a loop antenna. Our computational model predicts ablation zone extents within 1 ± 0.8 of ablation zones observed in experiments in ex vivo tissue. The maximum change in simulated ablation depths due to the presence of fibroids was 1.1 mm. In summary, this simulation study suggests that 1 - 3 cm diameter uterine fibroids can be expected to have minimal impact on the extent of microwave endometrial ablation patterns.