Ascites, defined as the abnormal accumulation of fluid in the peritoneal cavity, is mainly due to cirrhosis and portal hypertension (PHT). However, in 20% of cases, it is not related to these diseases. Given its varied etiology, it is essential to study it in order to determine therapeutic management. The pathophysiology of non-cirrhotic ascites is not usually related to cirrhosis-associated PHT, and understanding these mechanisms facilitates the etiologic diagnosis. Symptoms include abdominal distension, weight gain, postprandial fullness, and even dyspnea. The physical examination may be normal in cases of very mild ascites. An increase in abdominal circumference may be identified in more advanced or severe cases and signs associated with the underlying disease may also appear. The International Club of Ascites classification categorizes it according to the amount and abdominal distension. The initial evaluation includes a medical history, physical examination, abdominal ultrasound, and ascitic fluid analysis. Diagnostic paracentesis is crucial for identifying the cause, analyzing characteristics of the fluid such as its appearance and content, especially the protein concentration and the serum ascites albumin gradient, which will allow differentiating the different causes. In Western countries, the most frequent causes are tumor and heart diseases while in developing countries, infectious diseases, especially tuberculosis, are the most prevalent.