To evaluate the analgesic effect of intradermal sterile water blocks, 272 women in labor complaining of severe low back pain were randomly assigned to treatment with either sterile water or saline solution blocks. Pain intensity was assessed on a visual analog scale, before the blocks were given and again 1 and 2 hours later. The groups were equal with regard to age, parity, fetal size, progression of labor, and initial pain scoring. Pain scoring 1 and 2 hours after the blocks were given showed a significantly higher degree of analgesia in the sterile water group. No adverse effects were noted, and patient acceptability was high.