In assessing exocrine pancreatic insufficiency (EPI), its diverse etiologies and the heterogeneous population affected should be considered. Diagnosing this condition remains a challenge in clinical practice especially for mild-to-moderate EPI, with the support of the time-consuming breath test or the coefficient of fat absorption. The fecal elastase-1 test, less precise for the diagnosis, cannot be useful for assessing treatment efficacy. Pancreatic enzyme replacement therapy (PERT) is the mainstay of treatment, whereby enteric-coated mini-microspheres are taken with every meal, in progressive doses based on an individual's weight and clinical symptoms. The main indication for PERT is chronic pancreatitis, in patients who have clinically relevant steatorrhea, abnormal pancreatic function test or abnormal function tests associated with symptoms of malabsorption such as weight loss or meteorism. While enzyme replacement therapy is not recommended in the initial stages of acute pancreatitis, pancreatic exocrine function should be monitored for at least 6-18 months. In the case of unresectable pancreatic cancer, replacement enzyme therapy helps to maintain weight and improve overall quality of life. It is also indicated in patients with celiac disease, who have chronic diarrhea (in spite of gluten-free diet), and in patients with cystic fibrosis with proven EPI.