AIDS patients with minimal (group 1) or moderate (group 2) cognitive dysfunction (mental impairment) receive an increasing schedule of three dosage levels of peptide T. All patients receive an intravenous (IV) dose of peptide T for 10 days followed by the intermediate dose and then the highest dose, each intravenously for 10 days. Following successful completion of 3 IV doses, four patients participate in an intranasal pharmacokinetic (blood level study) dosage trial of 3 doses (different from IV) of peptide T once for each of 3 successive days. Follow-up continues for up to 1 year.