We measured blood pressure (BP) and heart rate in 1554 healthy infants and children aged 2 weeks to 5 years using an oscillometric device, to establish normative values in this age group. The BP cuff width was selected to be 40% to 50% of the circumference of the upper arm. Triplicate measurements of BP and heart rate were obtained in the waiting room of pediatricians' offices and well-baby clinics before the patients were examined by the physician or nurse. Three readings were possible in 87% of the infants less than 3 years of age and in all children 3 years of age and older. The average BP value (systolic/diastolic [mean]) increased rapidly from the 2- to 3-week value of 78/47 (59) mm Hg to the 1- to 5-month value of 95/60 (74) mm Hg. No subsequent increase in BP occurred until 2 years of age (96/56  mm Hg) when systolic and mean pressures started to increase at an average annual rate of 2 mm Hg for systolic pressure and 1 mm Hg for mean pressure until reaching the 5-year value of 104/58 (75) mm Hg. Diastolic pressure did not increase from 1 month to 5 years of age. Heart rate decreased with increasing age from the 2- to 3-week value of 153 to the 5-year value of 97 beats per minute. There was no difference in BP and heart rate values between boys and girls or among ethnic groups over the age ranges studied. Considering the high success rate in obtaining BPs in infants and small children, it appears that BP should be determined routinely, regardless of the age of the patients, when an oscillometric device is available.