Severity of microlithiasis- and sludge-induced pancreatitis in comparison to gallstone-induced pancreatitis has never been studied for a lack of definition. In this retrospective cohort study, 263 patients with acute biliary pancreatitis treated at a tertiary care center from 2005 to 2021 were stratified according to the recent consensus definition for microlithiasis and sludge. The gallstone-pancreatitis cohort was compared to microlithiasis, sludge, and suspected stone passage pancreatitis cohorts in terms of pancreatitis outcome, liver function, and endosonography/endoscopic retrograde cholangiopancreatography results using one-way analysis of variance and χ 2 test. Multinomial logistic regression analysis was performed to correct for bias. Microlithiasis- and sludge-induced pancreatitis, classified according to the revised Atlanta classification, did not present with a milder course than gallstone-induced pancreatitis ( P = 0.62). Microlithiasis and sludge showed an increase in bilirubin on the day of admission to hospital, which was not significantly different from gallstone-induced pancreatitis ( P = 0.36). The likelihood of detecting biliary disease on endosonography resulting in bile duct clearance was highest on the day of admission and day 1, respectively. Microlithiasis and sludge induce gallstone-equivalent impaired liver function tests and induce pancreatitis with similar severity compared with gallstone-induced acute biliary pancreatitis.