OBJECTIVE To determine whether variations in chloroprocaine placement in paracervical blocks influence effectiveness, whether chloroprocaine is superior to saline, and what factors influence pain perception. METHODS Eighty-two women undergoing first trimester aspiration abortions were randomized to receive 1% chloroprocaine or saline at 3-5-7-9 or 4-8 o'clock positions. Using a 0--10 scale, women rated anxiety, dysmenorrhea, and pain associated with laminaria insertion, paracervical block, and aspiration. RESULTS All four groups were similar in medical and demographic characteristics. Injection position did not influence pain ratings, but women who received chloroprocaine had less pain than those who received saline (6.3+/-2.3 vs. 7.8+/-2.0, P=0.002). Paracervical pain and dysmenorrhea were independently associated with aspiration pain scores (respective regression coefficients 0.49 and 0.26, P<0.008). CONCLUSIONS There is no advantage to using a four-site paracervical block over a two-site technique, but chloroprocaine is superior to saline. Paracervical block may not provide adequate anesthesia during first trimester abortion, especially for women with significant dysmenorrhea.