A cross sectional study was conducted to investigate the blood chemistry and platelet serotonin uptake as alternative method of determining HIV disease stage in HIV/AIDS patients. Whole blood was taken from subjects at the Human Virology of the Nigerian Institute of Medical Research. Subjects were judged suitable for the various investigations by means of a questionnaire. The Genie II HIV diagnostic kit was used to confirm HIV positive status. HIV positive subjects were grouped in to two: those receiving antiretroviral therapy were referred to as the ARV group and those not on antiretroviral therapy were designated as non-ARV group. Each group was further sub-divided according to the Centers for Disease Control 1993 classification of HIV disease. HIV negative subjects must have been tested no later than two months to the sample collection date and must not lead a high-risk lifestyle. Serum was used to assay for blood chemistry activities with Randox analytical reagents. Blood platelets were prepared from one milliliter of whole blood and platelet serotonin uptake rates were determined. The serum glutamic-oxaloacetic transaminase (SGOT) of non-ARV subjects was the only blood chemistry parameter that showed any significant variation from normal (p