Ten homosexual men received oral lithium carbonate at doses that maintained their serum lithium concentrations between 0.5 and 1.5 mEq/L. Prior to treatment all patients had HIV isolated from PHA-activated peripheral blood lymphocytes (PBLs) using a quantitative antigen-capture enzyme-linked immunosorbent assay (ELISA) assay for detection, and had an absolute number of CD4 (helper) lymphocytes of less than 300/mm3. Eight of 10 patients developed symptoms of drug toxicity requiring discontinuation of the drug in 7 patients. Two patients completed only 4-5 weeks of lithium therapy, and 5 patients received 7-8 weeks. All patients remained culture positive for HIV during the trial, and viral titers as measured by the antigen capture assay were unchanged or increased. There were no significant changes in the absolute number of CD4 lymphocytes, CD4/CD8 ratio, or phytohemagglutinin (PHA) or tetanus toxoid induced proliferative responses. There was a significant decrease in mixed lymphocyte reaction (MLR). Lithium carbonate demonstrated no immunorestorative or antiviral activity when given in therapeutic doses. Drug toxicity limited therapy in the majority of patients.