The ocular findings in 108 patients representative of all types of mucopolysaccharidoses (MPS) were reviewed. Attention was focused on optic nerve head appearance. Optic nerve head swelling was observed in 8/14 eyes of MPS 1-Hurler (MPS 1-H); 9/21 MPS 1-Hurler-Scheie (MPS 1-H-S); 0/4 MPS I-S; 13/66 MPS II; 1/22 MPS III; 0/58 MPS IV; 5/12 MPS VI; and 2/2 MPS VII eyes. In three patients, optic nerve head swelling was present in one eye and optic atrophy in the fellow eye; in four patients, optic atrophy followed disc elevation; three patients presented with bilateral optic atrophy. It was concluded that optic nerve head swelling precedes the development of optic atrophy in the systemic MPS.