In order to understand the clonal origins of recurrent hepatocellular carcinoma (HCC), as well as their clinical significance, the DNA contents of 44 resected recurrent HCCs from 21 patients were quantitatively measured using image analysis techniques. In 8 patients (38.1%), the recurrent HCCs had DNA contents which were obviously different from those in their primary tumors, suggesting new clonal origins; 13 (61.9%) had similar DNA contents, suggesting the same clonal origins. In these 2 groups, the mean intervals between 2 or 3 operations were 25 +/- 9.9 months and 7.9 +/- 3.1 months (P < 0.01), respectively, and the mean postoperative survival times were 51 +/- 20.8 months and 27.7 +/- 14.2 months (P < 0.05), respectively. The results indicate that the majority of recurrent HCCs originate from unresected fragments of their primary tumors, while some of them clearly originate from new tumor clones. Finally, reoperative resection is still considered an effective treatment for recurrent HCC, especially for those which originate from new tumor clones.