Reported baseline findings from the neurological assessment component of the Hemophilia Growth and Development Study (HGDS). HIV-positive (HIV+; n = 207) and HIV-negative (HIV-; n = 126) young males with hemophilia ages 6 to 18 years, were enrolled in a prospective study of their growth and development. At baseline, HIV+ and HIV- subjects were not significantly different in test performance. The number of subjects exhibiting below-average performance in three or more areas assessed was about 25% overall. For both groups, mean test scores were within the average range. Academic and adaptive skills were lower than expected based on mean IQ scores, and more behavioral/emotional problems than expected were reported by parents. Absolute CD4 cell counts per mm3 were not related to neuropsychological performance at baseline. Results suggest that the subjects with HIV were relatively free of HIV-related neuropsychological impairment at baseline and that observed differences from a general population reflect effects of hemophilia as a chronic illness.