The Hemophilia Growth and Development Study is a longitudinal examination of the changes in neuropsychological functioning, neurological functioning, physical growth and development, and immunologic status in otherwise healthy hemophiliac children and adolescents infected with human immunodeficiency virus (HIV) and in matched control groups of HIV negative hemophiliacs and male siblings of hemophiliacs. Participants are outside the neonatal age, being between 6 and 19 years of age at the time of entry to the study. 62% of the hemophiliacs enrolled in the study were infected with HIV solely through blood product usage during a limited time period predominately between 1978 and 1984. In April of 1997, the study began its eighth year of follow-up, retaining almost 50% of the enrolled cohort. The study was completed in May of 1998. An examination of patterns of physical growth have shown that stature among HIV-hemophiliacs was similar to that of children without hemophilia, although HIV+ children and adolescents were just over an inch shorter than HIV-hemophiliacs of the same age, and exhibited delays in skeletal maturation and pubertal advancement. Many analyses point to impacts related to hemophilia, apart from HIV, such as increased risk of muscle atrophy over time, and associations between hemophilia related morbidity and neuropsychological test performance. Longitudinal neurological follow-up of this patient population have indicated that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Coordination and/or gait abnormalities reflect hemophilia-related morbidity, not HIV-related neurological decline. Other results suggest that hemophiliac subjects, regardless of HIV status, have lowered performance in adaptive behavior and academic achievement, relative to IQ. Longitudinal neuropsychological results in non-perinatally HIV infected young persons support the hypothesis that declines in neuropsychological functioning are directly related to declines in immunological functioning. Careful studies of educational intervention will determine the most feasible and optimal strategies for closing the functional/potential gap in the children's achievements. Expanding the effort to examine the impact of HIV on CNS functioning, the 12th follow-up examination included "quantitative volumetric analysis of brain MRI " for willing study participants. The relationship of HIV related structural changes in the brain to functional impairments is poorly understood. This study seeks to investigate whether 1)MRI abnormalities are more common in the HIV positive subjects than in the HIV negative group, 2) changes in tissue volumes occur at the same rate over time in HIV positive and negative groups, 3) correlations can be made between neurological and neuropsychological function and changes in brain volumetric analyses, and 4) correlations can be made between HIV associated growth failure and members of the cohort who have grown and matured normally and hypothalamic/pituitary sizes. The results of this additional follow-up continue to be analyzed.