Background Ambulatory blood pressure monitoring (ABPM) has been shown to be more representative of blood pressure levels in adult patients than are casual measurements of blood pressure. To evaluate, by means of ABPM, the behavior of blood pressure in children with chronic renal failure submitted to continuous ambulatory peritoneal dialysis and compare the results with casual blood pressure monitoring measurements. Evaluation of blood pressures in chronically dialyzed pediatric patients by ABPM. Ten pediatric patients, treated by continuous ambulatory peritoneal dialysis were evaluated by ABPM using the oscillometric SpaceLabs 90207 monitor, every 10 min during the day and every 15 min during the night, for 24h. Six of 10 patients were found normotensive by office measurement of blood pressure; four of 10 patients were found hypertensive by casual measurements of blood pressure. With ABPM we obtained a mean success rate of 92.5%, confirmed hypertension in all the patients classified hypertensive in terms of office readings and reclassified six of six patients from normotensive to hypertensive. The mean systolic and diastolic physiologic falls in blood pressure at night were respectively by 10 and 15%. At the time of the ABPM study end-organ damage was present in two patients judged to be normotensive in terms of office blood pressures. Casual recordings of blood pressure are not representative of average blood pressure in dialyzed pediatric patients. ABPM seems to be a useful diagnostic aid for assessing treatment of hypertension in children with end-stage renal disease.