Hematocrit levels were determined in 36 mothers living at high altitudes (3,750 meters) and their infant cord bloods to determine the effect of maternal anemia on the infant. The arterial oxygen saturation (SaO(2)) and respiratory rate of the infants were also followed during the first four months of life. There was a negative correlation between maternal hematocrit and infant hematocrit (r(s) = - 0.57). Nineteen babies born to anemic women (hematocrit < 41%) had a significantly higher mean hematocrit (59.9%) than those born to non-anemic mothers (55.8%; P = 0.003). The SaO(2) levels and respiratory rates of infants were not different between infants born to non-anemic and anemic mothers. At high altitudes, infants from mothers with anemia have higher hematocrits than those born to non-anemic mothers.