Our prospective study of 350 amblyopic children divided them into three age groups: 2 to 5 1/2 years, 5 1/2 to 8 years, and 8 years and older. Treatment consisted of occlusion of the good eye. Compliance with treatment was analyzed by age group for the whole study population, but visual acuity results were evaluated only in children who complied fully with treatment and who cooperated at the initial visual acuity test with a Snellen chart. Younger children were significantly more compliant than older ones. This was probably the primary reason for the high incidence of treatment failure in older children. Children older than 8 years who complied with treatment showed a marked improvement in visual acuity--one almost as good as that in the younger children. A better initial visual acuity can be taken as a good prognostic sign, especially for this age group. In each group, most of the improvement occurred during the first three months of treatment. Improvement after this period was marginal.