Preoperative diagnoses were checked during surgery in 39 patients who underwent elective repeat Caesarean section with (n = 20) and without (as control, n = 19) a preoperative diagnosis of wall dehiscence (thinning) of the lower uterine segment (LUS). All patients were examined manually and by ultrasonography at 36 weeks gestation before labour. A preoperative diagnosis of wall dehiscence was made when the wall thickness was less than 2 mm and/or the patient felt pain and tenderness inthe LUS. Surgical findings of dehiscence were defined as a subperitoneal separation of the uterine scar in the LUS. The sensitivity and specificity of our ultrasonographic evaluations were found to be 100% and 83% (p < 0.05), respectively. On the other hand, there were no surgical findings of dehiscence in patients who felt pain and tenderness in the LUS with a wall thickness greater than 2 mm, nor among those in the control group.