Background & Aims: Almost one third of adults in the West have increased plasma levels of triglycerides. Even mild to moderate hypertriglyceridemia (2–10 mmol/L or 177–886 mg/dL) is associated with an increased risk of acute pancreatitis. However, it is not clear whether hypertriglyceridemia is a cause or result of acute pancreatitis. Lipoprotein lipase degrades plasma triglycerides. Variants in LPL, APOA5, APOC3, ANGPTL3, and ANGPTL4, which regulate the lipoprotein lipase pathway, result in increased or reduced plasma triglyceride levels. We investigated associations between these variants and acute pancreatitis in a study of the general population. Methods: In a prospective cohort study, men and women randomly selected from the area of Copenhagen were invited to complete a questionnaire, undergo a physical examination, and provide blood samples for biochemical and genetic analyses, from 2003 through 2015. We obtained triglyceride measurements from 117,427 participants. We examined for 15 genetic variants that are associated with lipoprotein lipase function in DNA samples from 102,888 participants and analyzed data from 117,427 participants in observational analyses. Diagnoses of acute pancreatitis (970 diagnoses among participants in the genetic analysis and 527 among participants in the observational study) were obtained from Danish registries. We performed a 1-sample Mendelian randomization analysis in which specific variants were used as markers of the plasma level of triglycerides to determine the association between the plasma level of triglyceride and acute pancreatitis. We calculated unweighted, internally weighted, and externally weighted allele scores for each participant by adding numbers of triglyceride-increasing alleles. Results: The highest genetic allele score correlated with a higher plasma level of triglycerides of 0.54 mmol/L (48 mg/dL). Among participants with the highest vs the lowest genetic allele score, the odds ratio for acute pancreatitis was 1.55 (95% CI, 1.08–2.23). Using instrumental variable analysis, integrating the effect of genotype on both triglycerides levels and risk of acute pancreatitis, we associated higher unweighted allele scores with an increased risk of acute pancreatitis (odds ratio [OR], 1.76; 95% CI, 1.16–2.65), as well as internally weighted higher allele scores (OR, 1.41; 95% CI, 1.01–1.97) and externally weighted higher allele scores (OR, 1.44; 95% CI, 1.01–2.04). Every 1 mmol/L (89 mg/dL) increase in triglycerides was observationally associated with an increase in OR of 1.09 (95% CI, 1.05–1.14) after multivariable adjustment. Conclusions: Based on an analysis of individuals with genetic variants associated with an increased level of triglycerides, via their effects on the lipoprotein lipase pathway, we associated an increased plasma levels of triglycerides with an increased risk of acute pancreatitis. Strategies to reduce plasma levels of triglycerides, by increasing lipoprotein lipase function, might be developed for prevention of acute pancreatitis.