Since its introduction, extracorporeal shock-wave lithotripsy (ESWL) has become the treatment of choice in patients with urinary calculi. But the pain during ESWL is intolerable for many patients. Tramadol HCL resembles morphine in that it depresses motor and sensory responses of the spinal nociceptive system by a spinal and a supraspinal action. The side effects of tramadol are less than morphine. A prospective study was performed to determine the effect of tramadol in ESWL for the patients with urinary tract calculi. Ninety patients were randomized divided into three groups. Group A 40 patients (male:female = 31:9) received oral tramadol HC1 100 mg; group B 17 patients (male:female = 12.5) received multi-vita; group C 33 patients (male:female = 26:7) received analgesic (contained aspirin 399 mg and codeine phosphate 15 mg). The patients took the drugs 30 minutes before ESWL. The patients with renal calculi > 2 cm in diameter or ureteral calculi > 1 cm in diameter were excluded. The lithotriper used in our hospital is Siemens Lithostar. According to the description of the patients postoperatively, the pain intensity during ESWL was identified with Verbal Scale and Visual Analogue Scale (VAS). The statistical method is one-way ANOVA. Statistical difference is significant when p < 0.05. The mean age of patients group A is 46.5 +/- 17.1, group B 45.5 +/- 14.4, and group C 50.5 +/- 14.6. The mean diameter of urinary calculi of group A is 0.98 +/- 0.41 cm, group B 1.09 +/- 0.33, and group C 1.06 +/- 0.43.(ABSTRACT TRUNCATED AT 250 WORDS)