A randomised multicentre clinical trial was undertaken to compare the effect on pain of indomethacin administered either intravenously or rectally to 116 patients with ureteric colic. Adverse reactions were also assessed. Of the patients receiving the intravenous injection, 48/53 (91%) achieved good pain relief (i.e. no supplementary analgesia was required) 30 min after administration, compared with 46/63 (73%) receiving the enema. Significantly more side effects occurred in the group treated intravenously. It was concluded that indomethacin administered as an enema was less effective than the intravenous form, but it should be regarded as a good alternative in the treatment of ureteric colic.