Methotrexate (MTX) has been shown to impair neurocognitive outcomes. Because the cumulative dose of MTX used in the standard treatment of osteosarcoma is higher compared to the treatment of other childhood cancers, we analyzed the neurocognitive performance among 12 survivors of childhood osteosarcoma exposed to high-dose MTX at our institution. Prospective longitudinal evaluations of neurocognitive functioning using the Japanese Wechsler Intelligence Scale for Children-4th Edition were performed. As a result, we observed age-appropriate development of neurocognitive performance among osteosarcoma survivors. In conclusion, cognitive development was not adversely affected in this cohort of childhood osteosarcoma survivors treated with HD-MTX.