Analysis of cellular hybrids confirms the assignment of alpha-L-fucosidase (alpha-FUC) to 1p in man. Discordant results are in favour of the following gene order: 1pter (ENO-1, alpha-FUC,AK2) PGM1 centromere Pep-C but give no information on the relative positions of ENO-1,alpha-FUC, and AK2. The assignments of alpha-FUC to chromosome 1 in the chimpanzee and to chromosome 4 in the African green monkey are demonstrated (chromosome nomenclature by Finaz et al, 1976). These results confirm the homology of chromosome 4 of the African green monkey and 1p of man and the chimpanzee.