Docosahexaenoic acid (DHA) regulates the lipid metabolism and inflammation that is closely associated with oxidative stress. The present study investigated the effects of DHA on the development of nonalcoholic steatohepatitis (NASH). To induce fatty liver, rats were fed choline-deficient high-fat diets (CDHF). The rats were then divided into 4 groups treated over the subsequent 6 weeks as follows: control, CDHF, CDHF+oxidative stress (NASH), and NASH+DHA (1.0 g/kg, p.o.). Rats of the control group were fed MF chow diet only. NASH rats showed severe steatohepatitis and liver fibrosis. Treatment with DHA significantly decreased the n-6/n-3 ratio in the livers and increased plasma SOD like activity compared with NASH rats. In addition, DHA attenuated the liver fibrosis during NASH development. Therefore, a higher DHA ratio in the liver of NASH rats might regulate the inflammatory response through a low n-6 ratio and diminished oxidative stress, effectively inhibiting liver fibrosis during NASH progression. These results suggested that DHA is a novel functional food for the prevention of NASH.