The diagnosis of ascites can be made very likely by a good clinical history and a well-directed physical examination, if the patient suffers from a disease which can cause ascites. The physician should ask about recent weight gain, change in abdominal girth and ankle oedema. With a positive history, the likelihood of the presence of ascites may increase 3 to 4-fold. When the findings at physical examination are also positive, the likelihood may increase 10 to 20-fold. A fluid wave is the most specific but less sensitive symptom. Shifting dullness, bulging flanks and flank dullness are less specific but much more sensitive parameters. The presence of ascites is very unlikely if the prior probability is low and both the patient's answers and the findings at physical examination are negative. Abdominal ultrasound, the gold standard, is not strictly indicated for diagnosing ascites: if based on the trial tried: pretest probability, clinical history and physical examination, the diagnosis is very likely or very unlikely. Ultrasonography is always indicated, however, when ascites is suspected and a positive finding is of clinical relevance.