The aim of the study was to compare the clinical efficacy of three different analgesic drugs with respect to their level of sedation, analgesia and quick mobilisation without cardiopulmonary depression, for outpatient extracorporeal shock wave lithotripsy (ESWL) procedure. Sixty outpatients undergoing elective ESWL using a third generation lithotriptor were studied. The patients were randomly divided into three groups of twenty patients. All patients received midazolam (2 mg) intravenously five minutes before the procedure. In group F, fentanyl was given (1 w g kg -1 IV) at the same time with midazolam. In group D, diclofenac sodium was given (1 mg kg -1 , IM) intramuscularly 45 minutes before ESWL. In group T, tramadol was given (1.5 mg kg -1 ) 30 minutes before ESWL. Arterial pressure, heart rate, respiratory rate and oxygen saturation were recorded before the procedure, after sedation, at the first minute, and every ten minutes during the procedure. Pain intensity was identified with a Visual Analogue Scale. The level of sedation was evaluated by using the Observer's Assessment of Alertness/Sedation Scale. All patients were asked to assess their satisfaction with the seven point Verbal Rating Scale before discharge. Side-effects were also recorded during the procedure. The incidence of nausea and vomiting was higher in fentanyl group compared with the other groups. In patients who received fentanyl, the decrease of oxygen saturation at the first and tenth minute of the procedure was statistically significant ( p < 0.05). Diclofenac sodium and tramadol were found to be safe and effective analgesics with lower side-effects than fentanyl.