Between 1965 and 1975, Shirodkar operations were performed on 144 patients (mean age 28,6 years). The most frequent diagnosis was incompetence of the internal cervical os, which accounted for 90% of the operations, the remaining 10% being prophylactic. Sutures were performed between the 14th and 16th week of gestation and 72,5% of these patients had normal births (mean gestation time 39 weeks). Without Shirodkar operation, out of 291 pregnancies studied, 26% resulted in normal birth; whilst with Shirodkar, 82% of 137 pregnancies were successfully delivered at term.