No significant differences were observed on the average number of pregnancies and livebirths, as well as on the frequencies of spontaneous abortions, stillbirths, premature children and those dying before the age of reproduction when the reproductive performances of 123 couples having at least one abnormal hemoglobin carrier were compared with the same number of appropriately chosen controls. The number of sibs of these carriers and of those with normal hemoglobin only did not differ significantly either. These and viability data reported elsewhere indicate essentially similar fitnesses for the individuals compared, who live in the nonmalarious environment of Porto Alegre. The fate of the Hb^s and Hb^c genes seems to be their gradual disappearance from this and other populations of the New World.