A randomized, double-blind study was carried out on forty patients with acute renal colic in order to evaluate the efficacy of Rowatinex in the treatment of patients with ureteric stones. Patients were randomized to Rowatinex and placebo tablets. In the Rowatinex-treated patients there was a significantly higher rate of expulsion of stones which were greater than or equal to 3 mm in diameter when compared with the placebo group (61% vs. 28%, respectively). A higher success rate (spontaneous stone expulsion and/or disappearance of dilatation of the collecting system on IVU) was noted in the Rowatinex group when compared to the placebo group (78% vs. 52%, respectively), although this was not statistically significant. No significant side effects were noted during the treatment with Rowatinex.