Two hundred four platelet counts for 105 infants between birth and 4 days of life were determined by phase microscopy. Resuits were analyzed for sex, race, weight and age, without any significant difference in counts being found. No significant trend (increase or decrease of the platelet count) during the period of study was demonstrated. The platelet count as determined by phase microscopy for the normal neonate during the first 4 days of life is 200,000 ± 100,000/mm3.