Nocturnal enuresis is a common childhood disorder. Tricyclic antidepressants and anticholinergic agents have been the well accepted pharmacological treatment for this disorder and are efficacious in 40-70% and 10-50% of cases, respectively. The present study was performed to evaluate the effect of a combined treatment of tricyclic antidepressant and an anticholinergic agent. Twenty-two children aged 6-12 years with primary monosymptomatic nocturnal enuresis who did not prefer to use a conditioning alarm were given a combined treatment of these drugs. After a control period of 1 month, each patient was treated for 6 months and then observed for 3 months. A 30-mg dose of amitriptyline or imipramine was given with either 2-4 mg oxybutinin or 10-20 mg propiverine. Efficacy was determined relative to the number of wet nights per week compared with the control period, with more than a 50% decrease in wet nights per week taken to indicate efficacy. The mean wet nights per week decreased from 6.1 to 1.7 (P<0.01), and efficacy was established in 20 patients (90.9%). Relapses occurred in 60.0% of patients during the follow-up period. No significant side effects were observed. The efficacy of the combined therapy in monosymptomatic nocturnal enuresis appears to be greater than that reported for either drug alone, and therefore can be a choice of treatment in order to motivate children with nocturnal enuresis.