A total of 974 preschool children aged 3 to 5 years in the city of Nahariya, Israel had their blood pressure measured during the 1983-84 school year. Charts of selected percentiles of blood pressure were developed, and distribution curves were drawn. Mean systolic pressure increased with age--though not significantly--in both sexes, and it tended to be higher in boys than in girls. The mean diastolic pressures increased slightly with age in both sexes, but no differences were found between boys and girls. The mean diastolic pressures in this survey were significantly lower than those reported in other studies, presumably because we used the fifth Korotkoff sound for determination of diastolic pressure instead of the fourth, as was done in most other studies. The percentiles of blood pressure in our study indicated for both sexes that systolic blood pressure above 108 mm Hg at age 3, 110 mm Hg at age 4 and 112 mm Hg at age 5 and diastolic pressures above 62, 64 and 68 mm Hg, respectively, must be considered abnormal.