We investigated the effects of habitual exercise and diet restriction on the hepatic fat accumulation in Zucker fatty rats. Male 6-week-old Zucker fatty rats were divided into obese (Ob), diet restriction (DR), and diet restriction + exercise (DR + Ex) groups. Male Zucker lean rats (L) were used as a control group. The rats in the L and Ob groups were maintained on ad libitum diets. The rats in the DR and DR + Ex groups were fed a 30% restricted diet. The rats in the DR + Ex group exercised voluntarily on a wheel ergometer. After 6 weeks of intervention, the serum free fatty acid and leptin levels in the Ob group were significantly higher than those in the L group. In the Ob group, the hepatic triglyceride content was higher than that in the L group and hepatocyte fat infiltration was observed on haematoxylin and eosin staining. These changes were suppressed by DR + Ex, but not by the DR intervention. These results suggest that habitual exercise inhibits fat accumulation in the liver of Zucker fatty rats.