The corticotropin-adrenocortical response to cold pressor challenge was investigated in a study of human immunodeficiency virus (HIV) infection. Data obtained from 16 HIV-1-positive and 28 HIV-1-negative subjects are presented in this report. After the insertion of a venicatheter and following 30 min of rest, the subjects immersed one of their hands in an ice-water mixture for 2 min, and serial blood samples were obtained for the determination of ACTH and cortisol levels. The results show a significant blunting in the ACTH response and marginally lower levels of cortisol, over all time points, in HIV-1-positive subjects compared to that in HIV-1-negative subjects.