Hypertension is frequent in pediatric patients receiving dialysis, with an especially high rate reported in children on hemodialysis (HD). We performed the present study to assess blood pressure (BP) status and identify risk factors for poor BP control in children on maintenance HD. One month's dialysis records were collected from 71 subjects receiving HD in ten dialysis units participating in the Midwest Pediatric Nephrology Consortium (MWPNC). For each HD session, data on pre- and posttreatment weights and BPs were recorded. Hypertension, defined as mean BP >or= 95th percentile, was found in 42 (59%) subjects. Eleven subjects (15.5%) had prehypertension, defined as mean BP between the 90th and 95th percentiles, while 18 subjects (25.3%) had normal BP (<90th percentile). BP significantly decreased at the end of a dialysis session; however, only 15 of 42 hypertensive subjects (35%) normalized their BP. Hypertensive subjects were younger (p = 0.03), had higher serum phosphorus (p = 0.01), and had more elevated posttreatment weight above estimated dry weight (p = 0.02). Logistic regression showed that younger age (p = 0.02) and higher serum phosphorus (p = 0.02) independently predicted hypertensive status. In conclusion, this study emphasizes the difficulty of BP control in pediatric HD patients. Especially poor BP control was found in younger children; those patients who do not reach their posttreatment weight goals, perhaps reflecting their hypervolemic state; and those who have higher serum phosphorus levels.