Seventy-eight women underwent induced mid-trimester abortion. Fifty-two women aborted after an intra-amniotic injection of 1 g oxytetracycline hydrochloride. The control group comprised 16 women who received an intra-amniotic injection of hypertonic saline and 9 women with prostaglandin F2 alpha. All but 2 women aborted after one injection. Thirty-five women of the oxytetracycline hydrochloride group received intravenous oxytocin after the appearance of uterine contractions, 17 did not. The mean injection abortion interval in the women who received intravenous oxytocin was 38.6 +/- 2.7 h, whereas in the group without oxytocin it was 31.3 +/- 2.3 h. There is no statistically significant difference between these two groups (p less than 0.2). The mean injection abortion interval in the hypertonic saline group was 18.4 +/- 2.2 h. In the F2 alpha group it was 13.2 +/- 1.3 h. There is no statistically significant difference between hypertonic saline and prostaglandins (p less than 0.2). The mean injection abortion interval is significantly shorter in the F2 alpha and hypertonic saline groups as compared to the oxytetracycline hydrochloride group (p less than 0.001). It is advisable therefore to use oxytetracycline hydrochloride only in cases when the use of F2 alpha or hypertonic saline is contraindicated.