Background and aim: Nonalcoholic fatty liver disease (NAFLD) is a burgeoning medical problem all over the world.Its prevalence is about 15％ in adults of mainland China.A nonsynonymous single nucleotide polymorphism (SNP) rs738409 (I148M) in patatinlike phospholipase domain-containing protein 3 (PNPLA3) was reported to increase the susceptibility of NAFLD in China.We aim to investigate whether this variation is associated with the degree of fat liver in Chinese adults.