To determine the normal values of P wave duration and P dispersion (Pd=maximum P wave duration-minimum P wave duration) in healthy children, electrocardiograms of 232 healthy children (143 boys, 89 girls, aged 7 to 15 years) were examined. There was no significant gender difference in maximum P wave duration (103+/-9.5 msec vs 102+/-8.4 msec, p=0.23) or P dispersion (27.2+/-5.3 msec vs 26.8+/-6.2 msec, p=0.643). Maximum P wave duration (r=0.23, p<0.01) and P dispersion (r=0.16, p<0.01) were related to age. We conclude that age affects the P wave duration and P dispersion in healthy children, and thus, should be taken into account when maximum P wave duration and P dispersion are considered for any purpose in healthy children.