We reviewed the records and statistics of 560 patients hospitalized with hepatocellular carcinoma (HCC) over a 5-year period. One hundred and forty-one patients (26%) had spontaneous rupture of their HCCs. Different characteristics of the rupture (R) and nonrupture (NR) groups were compared; there were statistically significant differences (p < 0.05) in the size of the tumor (R, 9.83 +/- 4.36 cm, and NR, 7.67 +/- 4.01 cm; p < 0.0001), and the minimal thickness of peritumor liver parenchyma (R, 0.03 +/- 0.20 cm, and NR, 0.30 +/- 0.70 cm; p < 0.001), the presence of the ¿hump sign¿ (R, 87.8%, and NR, 45.7%; p < 0.0001), and the minimal thickness of peritumor liver parenchyma (R, 0.03 +/- 0.20 cm, and NR, 0.30 +/- 0.70 cm; p < 0.001). The percentage of left-lobe tumors was significantly higher in the rupture group than in the nonrupture group (p < 0.05). In addition, the Child-Pugh's score and serum transaminase levels were higher, and the prothrombin times more prolonged, in the rupture group. Factors that were not statistically significant included sex, age, etiology of cirrhosis, platelet count, portal vein thrombosis, and the presence of a varix. Multivariate logistic regression analysis indicated that the tumor size, the presence of a hump sign, and the Pugh's score correlated the best with HCC rupture (p < 0.05). Ninety-four patients from the rupture group died during hospitalization. The mortality rate was 66.7%. We conclude that (a) spontaneous rupture of HCC is a likely sequel of progressive expansion of tumor that finally protrudes outside the liver surface and hemorrhages, (b) left-lobe tumor presents a higher risk of rupture, and (c) portal hypertension does not play a major role in the pathogenesis of tumor rupture.