Abstract To assess the factors related to the quality of ambulatory blood pressure monitoring in a pediatric population, we performed 24-h ambulatory blood pressure monitorings on 333 unselected children aged 3 to 18 years using a Spacelabs 90207 monitor. For each individual, the percentages of valid measurements (ratio between valid and total number of measurements, 76.4% ± 15.6%) and of successful measurements (percentage of valid preset measurements, 89.8% ± 11.5%) were calculated. Two hundred eighty-one (84.1%) monitorings had a successful measurement rate of >80%. Two hundred thirteen (64%) were of excellent quality, as defined by the percentage of successful measurements being higher than or equal to 90%. Age ( P < .0001) and 24-h systolic blood pressure ( P < .04) were positively and independently associated (in multiple regression analysis) to the percentage of successful measurements, accounting for 8% of the variance. Furthermore, a significant negative correlation between causal pulse pressure and the number of erroneous measurements was observed (r = −0.18, P < .01). This study has shown that in a pediatric population, the quality of the monitoring depends only in part on age and ambulatory systolic blood pressure values when an oscillometric device is used. The results have demonstrated the important role pulse pressure amplitude plays when accounting for the number of erroneous measurements.