An analysis was performed on data collected under the NHLBI-sponsored multicenter study entitled 'Pediatric Pulmonary and Cardiovascular Complications of Vertically Transmitted Human Immunodeficiency Virus (HIV) Infection' and abbreviated P2C2. The P2C2 study was performed in a prospectively defined cohort of 150 children with HIV infection and 350 uninfected control children born to HIV infected women who had been followed since the first month of life to provide understanding of cardiac dysautonomia in early HIV infection. In addition, 198 children with symptomatic HIV infection were analyzed to provide an assessment of cardiac dysautonomia in later stages of pediatric HIV infection. Heart rate spectral analyses were performed on 2196 Holter monitor recordings from these patients followed at the five P2C2 clinical centers to capture noninvasively the time varying contributions of the sympathetic and parasympathetic nervous system to the control of heart rate throughout the course of a day. The spectral balance parameters and the changing response of heart rate to the electrocardiogram-derived respiratory signal characterized the responsiveness of the sympathetic and parasympathetic nervous system at rest and during the events of a normal day. Autonomic function data were electronically transmitted to the P2C2 data coordinating center at the Cleveland Clinic and analyzed along with other P2C2 data (eg. infectious, immunologic, growth, renal, neuroendocrine, pulmonary and cardiac) to determine their risk factor potential for cardiac dysautonomia.