We present incidence estimates for amblyopia using data from a study of a cohort of 364 children from a single English county who were referred during 1983 for occlusion therapy. Using a criterion of a visual acuity of 6/12 or worse to define amblyopia, we estimate that 3.0% of the county's children develop the condition. Successful treatment of some of these children means that 1.9% will remain amblyopic as adults.