We investigated the activity of LAK cells in 10 patients with chronic persistent hepatitis, 20 patients with chronic active hepatitis, 21 patients with post-hepatitic cirrhosis and 21 normal persons. The values were 36.87 +/- 7.44, 30.38 +/- 5.36, 28.84 +/- 4.95 and 44.50 +/- 4.75 respectively (P < 0.05). The LAK cell activity in patients with chronic hepatitis was lower than that of normal persons, especially in those with chronic active hepatitis and post-hepatitic cirrhosis. The causes of lower LAK cell activity in patients with chronic hepatitis were less expression of IL2 receptors on precursors of LAK cells and existing serum LAK cell inhibition factors. We further studied 9 patients with chronic hepatitis B treated with autologous LAK cell transfusions. Factors favoring a more effective result were female sex, ALT elevation after treatment, activity of LAK cells > 10%, and inhibition factor of LAK effector cells existing in serum of patients, with inhibition rate < 50%. These factors might be used as the indications in selecting cases for treatment and predicting the effect of the treatment. As the number of cases observed was rather small, further investigation is needed.