We report two cases of severe dengue fever in persons returned from stays in endemic areas during the summer outbreak of 2010. Both presented a hemorrhagic syndrome associated with primary hemostasis disorders, neutropenia, and severe hepatic cytolysis without any hepatocellular insufficiency. Three days after hospitalization, the first patient's AST and ALT levels rose to 80 and 12 times the upper reference values respectively, and the second patient's to 12 and 7 times those values. The second also presented signs of hemodynamic shock. Our observations suggest that the combination of severe hepatic cytolysis and hemostatic disorders may be a predictive marker of the severity of dengue fever. The pathophysiologic mechanisms explaining this severity remain unknown.