The authors studied the levels and evolution of systolic, mean and diastolic arterial blood pressure in term newborns adequate for gestacional age during the first month of life. The applied technique was oscillometric, using a non-invasive monitor. The study was prospective, including newborns who had received first minute Apgar score above 6, with no clinical disturbances or use of any drug with possible arterial blood pressure side effects. The measurements of systolic, mean and diastolic arterial blood pressure were taken at 12 hours of life and 3rd, 7th, 14th and 28th days of life. The authors observed an increase in arterial blood pressure mean values from the 1st to the 7th day of life and that there was no significant changes on the same measurements from the 1st to the 4th week of life.