Aim was to explore the effect of nonalcoholic fatty liver as a hepatic manifestation of metabolic syndrome on the severity of acute pancreatitis. We hypothesized that patients with nonalcoholic fatty liver would have a more severe form of acute pancreatitis. We retrospectively analyzed 822 patients hospitalized with acute pancreatitis. We diagnosed acute pancreatitis and determined its severity according the revised Atlanta classification criteria from 2012. We assessed nonalcoholic fatty liver with computed tomography. There were 198 (24.1%) patients out of 822 analyzed who had nonalcoholic fatty liver. Compared to patients without nonalcoholic fatty liver, patients with nonalcoholic fatty liver had significantly higher incidence of all components of metabolic syndrome. Patients with nonalcoholic fatty liver had statistically higher incidence of moderately severe (35.4% vs. 14.6% ; p =0.02) and severe acute pancreatitis (20.7% vs. 9.6% ; p < 0.001) compared to patients without nonalcoholic fatty liver. At the admission patients with nonalcoholic fatty liver had higher values of C-reactive protein as well as at day three, higher APACHE II score at admission and significantly higher incidence of organ failure and local complications as well as higher values of computed tomography severity index compared to patients without nonalcoholic fatty liver. We found independent association between the occurrence of moderately severe and severe acute pancreatitis and nonalcoholic fatty liver (OR 2.13, 95% CI 1.236–3.689). Compared to patients without nonalcoholic fatty liver, patients with nonalcoholic fatty liver had a higher death rate, however not statistically significant (5.6% vs. 4.3% ; p=NS). Presence of nonalcoholic fatty liver at admission can indicate a higher risk for developing more severe forms of acute pancreatitis and could be used as an additional prognostic tool.