The aim of this study was to assess the relationship between bladder dysfunction and impaired cardiovascular reflexes in diabetic children with no clinical symptoms of autonomic neuropathy. After 15 ml/kg of water intake, the time to first sensation to void, the voiding volume, the voiding time, the average and maximum urinary flows, and the time to maximum urinary flow were estimated by sonography and uroflowmetry in diabetic children with and without cardiovascular autonomic dysfunction (CAD), and in a healthy control group. The three groups of children were matched for age, weight and height. CAD was considered to be present if the results of cardiovascular tests were more than 2SD from the mean of healthy controls. Diabetic children with and without CAD had increased time to first sensation to void, voiding volume, and average urinary flow when compared with healthy children. Voiding volume and average and maximum urinary flows were higher in diabetic children with CAD than in those without CAD. Diabetic children with CAD had also a higher maximum urinary flow than diabetic children without CAD and healthy children. Diabetic children with CAD had a longer diabetes duration and a higher mean fructosamine level during the preceding 3 years than those without CAD. These findings suggest that diabetic children may have diminished sensation of bladder filling independent of impaired cardiovascular reflexes, however, the degree of bladder dysfunction parallels with CAD, both depending on diabetes duration and long-term glycaemic control.