The present paper reports the epidemiological, clinical, urodynamic and cystographic data of 100 consecutive patients (mean age 9.59 years) with nocturnal enuresis. These patients were divided into three groups: group I (4 to 7 years old), 23 patients; group II (8 to 11 years old), 51 patients; and group III (12 to 14 years old), 26 patients. Nocturnal enuresis was more frequent in group II (51%). It was more prevalent in males (51%) of groups I and II. Isolated nocturnal enuresis was more frequent (54%) than nocturnal enuresis associated with diurnal symptoms (46%) in all age groups. Urinary infection was observed in 16% and was more prevalent in girls (68.7%). Detrusor instability was the most common urodynamic finding (40%), particularly in group II and girls. Uncoordinated voiding was the second most common urodynamic finding (24%), particularly in group II and girls. Lower urinary tract infection was observed in 1% (males). No abnormal urodynamic data were observed in 19%. Neurogenic bladder was observed in 16%, mainly in group II (31%). Vesicoureteral reflux was detected in 18%, mainly in girls (66.6%) and a postvoiding residual urine in 10%. A diagnostic and prognostic system and a therapeutic strategy based on our data are proposed.