Six new patients with the Cohen syndrome are reported from Finland and 25 published cases from elsewhere are reviewed. New findings are consanguinity among two pairs of parents, granulocytopenia, and marked ophthalmological changes: decreased visual acuity, hemeralopia, constricted visual fields, chorioretinal dystrophy with bull's-eye-like maculae and pigmentary deposits, optic atrophy, and isoelectric electroretinogram. Previously known features of the Cohen syndrome (non-progressive mental retardation, short stature, microcephaly, peculiar facies, slender hands and feet, floppiness, delayed puberty) are confirmed or revised. The ophthalmological features merit attention in the previous and future suspected cases of the Cohen syndrome. Autosomal recessive inheritance can be taken for granted.