To search for a morphologic biomarker to differentiate between pathologic myopia and simple childhood myopia. Retrospective case series. The study included children (age ≤15 years) with high myopia (as defined by the Japanese Ministry of Health and Welfare) who attended the High Myopia Clinic between April 1982 and March 1994, had undergone fundus photography, and had a follow-up of 20 years or more. Fundus photographs obtained in childhood and adulthood were examined for presence of pathologic myopia, defined by high myopia (myopic refractive error >8 diopters or axial length ≥26.5 mm) and the presence of stage 2 or higher myopic maculopathy. Myopic maculopathy in childhood. The study included 56 eyes of 29 patients with a mean age of 10.2±3.6 years at the initial visit and an age of 36.0±7.6 years at the last visit. Mean axial length was 27.0±1.4 mm at baseline and 29.7±2.0 mm at the last visit. At the last visit, 19 eyes (34%) had tessellated fundus alone, 31 eyes (55%) had diffuse chorioretinal atrophy, 3 eyes (5%) showed patchy chorioretinal atrophy, and 1 eye (2%) had macular atrophy. Thus, 35 eyes (63%) had pathologic myopia in adulthood. Among the 35 eyes, 29 (83%) already had diffuse chorioretinal atrophy at the initial visit in childhood and the remaining 6 eyes (17%) showed tessellated fundus in childhood. The diffuse chorioretinal atrophy seen in childhood was restricted to the area temporal to the peripapillary region. The presence of peripapillary diffuse chorioretinal atrophy in children with high axial myopia may be an indicator for the eventual development of advanced myopic chorioretinal atrophy in later life. These features in children may be helpful for differentiating simple childhood myopia from eventual pathologic myopia.