We have determined the degree of abnormalities in serum copper concentrations in HIV-seropositive individuals. The study was conducted at the Virgen de las Nieves Universitary Hospital in Granada (Spain). A total of 142 HIV-infected individuals and 84 control subjects were included in the study. The HIV-infected subjects were divided into three groups following the 1993 criteria of the Center for Disease Control and Prevention (Atlanta, USA). Serum copper levels in HIV-infected subjects were significantly higher than those found in control individuals (P<0.001). Moreover, there were no statistically significant (P>0.05) differences in serum Cu levels among the three groups considered although serum Cu enhancement occurred at the beginning of the infection process (group A). This increase then remains constant in advanced stages of HIV infection (groups B and C). The mean serum Cu concentration in women (1.41 mg/l) was not significantly higher than that found in men (1.39 mg/l) (P>0.05). Linear regression analyses between serum copper concentrations and nutritional or biochemical indices (prealbumin, albumin, transferrin, lymphocytes CD4, body mass index, weight) were not statistically correlated (P>0.05). These data suggest that copper which is an acute phase reactant, may be a useful marker of HIV activity and progression to AIDS as in other chronic infective diseases.