Twenty-four-hour ambulatory blood pressure monitoring (ABPM) has proven to have better reproducibility than office blood pressure (BP) and is increasingly used for the study of hypertension in children and adolescents. The aim of our study was to assess 24-h BP profiles and to compare the results of office BP measurements with ABPM in stable liver transplant recipients transplanted before the age of 18 yr. ABPM was performed in 29 patients (nine males, 20 females), aged 3.9-24.8 yr (median 10.8 yr). The investigation was conducted 1.1-11.5 yr (median 5.1 yr) following transplantation. ABPM confirmed hypertension in one out of three office hypertensive patients. Seven patients (24%), whose office BP recordings were within the normotensive range, were reclassified as hypertensive. Non-dippers (n = 17), arbitrarily defined as patients with less than 10% nocturnal fall in BP, were similarly distributed among patients with ambulatory normotension and ambulatory hypertension (chi(2), p = 0.79). In addition, non-dippers showed a negative correlation between 24-h total urinary albumin excretion and both systolic and diastolic nocturnal decline in BP (Rho = -0.48, p < 0.05 and Rho = -0.86, p < 0.01, respectively). Our study found office BP readings to be poorly representative of 24-h BP profile. Larger studies are needed to confirm our observations as well as to determine whether routine BP measurements in the follow-up of paediatric liver transplant recipients should be based solely on office BP.