A review of the literature on the subject since 1956 is made in connection with a presentation of ten new cases from northern Sweden. Nine of these are related to the main pedigree published in 1956. Consanguinity between the parents has been established in two of the new families. The clinical course was identical to that described in 1956. A few additional details are presented. The granulocytopenia is present on the first day of life and the granulocyte count subsequently rapidly decreases during the first week. The existence of a diaplacental factor is regarded highly probable. It is assumed that the maturation defect in the granulocyte precursors may be due to deficiency of a serum factor. The fact that many cases of infantile genetic agranulocytosis occur sporadically is finally explained.