To estimate the influence of fever, diarrhoea, stage of HIV disease, opportunistic infection and anorexia on malnutrition in HIV-infected patients we analysed data of patients undergoing a nutritional counselling programme from November 1989 to April 1992.Our study group comprised 104 HIV-infected patients (98 homosexual men, 15 asymptomatics, 30 AIDS-related complex patients, 59 AIDS patients). Nutritional status was measured by previous weight loss, bioelectrical impedance analysis and prospective intake protocol.Patients had lost 10 +/- 8.7% of body weight. Compared with controls, body mass index was lower (P < 0.001), and extracellular/body cell mass ratio (ECM/BCM) was higher (P < 0.001). BCM was reduced proportionately to weight loss, percentage of body fat was lower compared with controls (P < 0.001), even in patients with stable weight. Clinical risk factors for malnutrition were identified as fever in 31, diarrhoea in 26, acute infections in 42 and anorexia in 73 out of 104 patients. One single risk factor was predominant in 63 patients: fever in five, diarrhoea in 14, acute infections in 17 and anorexia in 27 patients. Weight loss was not linearly correlated to CD4 count or to time since AIDS diagnosis. Food intake was highly variable (39-165% of calculated needs) without correlation to weight loss.Loss of body fat was found even in the earlier stages of HIV infection and was more severe than loss of BCM. Important risk factors for malnutrition are anorexia (most frequent), diarrhoea and fever (most severe). Most patients have combined risk factors. Treatment strategies and pathophysiologic studies should consider the heterogeneity of HIV-associated malnutrition.