Acute lymphocytic leukemia (ALL) is one of the most common types of pediatric cancers. Improvements in treatment within the last 20 years have resulted in reduced mortality and a greater focus upon quality of life. Several researchers have documented neuropsychological impairments in children following treatment for ALL; however, there have not been any comparative studies documenting differences in neuropsychological functioning based upon treatment modality despite the documented effects of radiation therapy and combined radiation/chemotherapy upon the developing brain. In addition, past studies have focused on unitary measures, ignoring the hierarchical relationship between basic cognitive functions and more abstract skills. This study examined the neuropsychological functioning of 81 children who were treated for ALL at a metropolitan children's hospital. All children were tested a minimum of two years after the final treatment session and were administered the NEPSY. Results do not support any interactions or main effects with the exception of the age of the child at diagnosis. Children diagnosed prior to the age of 5 showed greater impairments on tasks measuring attention, memory, and visuospatial reasoning in comparison to peers diagnosed after age 6.