Risk for the development of liver disease was estimated in 115 adults with alpha 1-antitrypsin deficiency, most of whom were of PI type (protease inhibitor type) Z. Seventy-one subjects were ascertained through their disease; 44 were ascertained independently of disease. A low concentration of serum prealbumin was sensitive in detecting impaired liver function and may indicate functioning cell mass, a different parameter than is measured by liver enzymes. Liver disease has usually been considered rare in adults with alpha 1-antitrypsin deficiency. However, the risk for the development of liver disease was relatively high for men between 51 and 60 years of age. The risk for women was lower than that for men. Our study indicates that a periodic assessment of liver function may be warranted for patients with alpha 1-antitrypsin deficiency who are over 40 years of age.