1. Thirteen cases of Pelger-Huët anomaly occurring in three families are presented and discussed. The second recorded case of the anomaly in Negroes is included; the occurrence of familial hereditary elliptocytosis in this same family and the possible relationship to the Pelger-Huët anomaly are discussed.
2. Certain less well-known facts about Pelger-Huët anomaly are considered in relation to the cases presented.
3. The survival time of transfused neutrophils in the peripheral blood was investigated using the anomaly as a tagging device. Most of the cells were found to be absent from the peripheral blood stream in 6 to 8 hours, and none was found after 49.5 hours.