We report on a boy with prenatal growth retardation, progressive pancytopenia, cerebellar hypoplasia, microcephaly and developmental delay. Despite extensive laboratory investigations, no specific cause for the abnormalities could be revealed. Strikingly similar features have been described in two brothers by Hoyeraal et al. [5] in 1970 and in one boy by Hreidarsson et al. [6] in 1988. The features seem to be part of a separate entity, for which the eponym "Hoyeraal-Hreidarsson syndrome" may be used. An autosomal or X-linked recessive mode of inheritance seems likely.