Limited information is known about neuropsychological outcomes in Alexander disease, a rare leukodystrophy. Two pediatric cases are summarized. Case 1 (evaluations at 6, 7, 9, and 12 years of age) represents Type I Alexander disease with associated seizures. Case 2 (evaluations at 12, 13, and 16 years of age) represents Type II Alexander disease without additional complications. Case 1 experienced declines in intellectual functioning, visual motor skills, receptive vocabulary, verbal memory, and academic achievement. Case 2 experienced variable neurocognitive change and academic functioning, with average word reading and spelling. Verbal memory also remained intact. Taken together, individuals with Alexander disease may experience cognitive decline to variable degrees. Type I Alexander disease, associated with earlier onset and additional neurological complications, may presage greater cognitive decline than Type II. Due to variability in functioning over time, it is critical to follow individuals across development to make recommendations for educational and treatment planning.