This contribution describes the performance of a transethmoidal decompression of the optic nerve in a 5 1/2-year-old boy with marble bones (osteopetrosis, Albers-Schönberg disease). As a result of the operation the function of the eye still with vision was maintained in an unvarying good state over a follow-up period of some 5 years. In the literature only one other case of this diagnosis has been reported in which such an operation was successfully performed, though in that case with craniotomy. The procedure reported here was the first in which the transethmoidal approach was used, which puts less strain on the patient. In addition to the description of the case the problems involved are discussed.