Quantitative determinations of serum alpha-fetoprotein (AFP) in 96 patients with hepatomas have demonstrated three main groups based on changes in the serial levels: 1) patients with more than 10 000 ng/ml during most of their clinical course, and with an increase of 10 000 ng/ml or more in a week (Group A); 2) patients with levels varying from 200 to 10 000 ng/ml and with an increase of 1000 ng/ml in three to four months (Group B); and 3) patients with serum AFP level below 200 ng/ml during most of their clinical course (Group C). The patients in Group A had a mean survival time of 7.62 +/- 3.97 months, and those in Group B, 16.18 +/- 12.18 months. The patients in Group C were subdivided into two groups according to whether survival time was long (33.92 +/- 28.22 months) or short (3.75 +/- 0.87 months). Histologic findings revealed poorly differentiated carcinoma in patients in Group A, moderately differentiated carcinoma in those in Group B, and well differentiated carcinoma in those with long survival in Group C and anaplastic carcinoma in those with short survival in Group C.