Forty-five patients with alcoholic cirrhosis, 20 chronic alcoholics with normal liver function tests and 36 healthy subjects were investigated. A combined index of nine anthropometric and biochemical parameters (triceps skinfold, arm muscle circumference, mid-arm muscle area, body fat percentage, creatinine-height index, serum albumin, plasma transferrin, prealbumin and retinol-binding protein levels) was used to evaluate nutritional status, allowing a distinction to be made between those patients with adequate nutrition (group I: 40 per cent of cirrhotics and 55 per cent of alcoholics), those with slight malnutrition (group II: 37.7 per cent of cirrhotics and 45 per cent of alcoholics) and those with severe malnutrition (group III: 22.2 per cent of cirrhotics and none alcoholic). Natural Killer (NK) cell activity of peripheral blood lymphocytes was determined using a 51Cr releasing cytotoxicity assay against K562 target cells. This was significantly lower in the cirrhotics than in the controls and chronic alcoholics (P less than 0.001 and P less than 0.01 respectively), but there was no difference between the latter two groups. Natural Killer activity was significantly lower in samples obtained from cirrhotics with severe malnutrition than in those with adequate nutrition, suggesting that malnutrition may play a role in the onset of the immunological disorder. No relationship could be established between nutritional status, NK activity and the clinical activity of the disease using Orrego's index on the liver function tests.