Primary biliary cirrhosis (PBC) is likely an autoimmune disease that destroys the interlobular bile ducts. Although the term PBC implies cirrhosis, this is not always present. The condition may be entirely silent clinically, save for the hallmark mitochondrial antibodies in serum. The clinical spectrum of PBC ranges from asymptomatic anicteric cholestasis with or without extrahepatic manifestations to severe cholestasis with decompensated cirrhosis. It is uncertain whether or not the course of this disease is universally fatal. Currently, no specific features have been identified which predict progression from asymptomatic to symptomatic disease, although once hyperbilirubinemia is present, a rising level indicates a poor prognosis. The liver-specific complications include pruritus, abdominal pain, xantholasma, and portal hypertension. The latter is often an early feature, as the portal hypertension is presinusoidal in nature and, when present, does not always reflect the presence of cirrhosis. There are many extrahepatic features of PBC, the most common being metabolic, chiefly hypothyroidism and metabolic bone disease. Other common associations are rheumatologic, renal, pulmonary, neuromuscular, and dermatologic. The non-specific yet distressing symptom of fatigue affects up to two-thirds of PBC subjects, but its etiology remains obscure.