Intrahepatic cholestasis of pregnancy is characterized by skin pruritus and a biochemical cholestasis of mild to moderate severity appearing during pregnancy (mainly in the third trimester) and disappearing after delivery. It recurs in 40-60% of future pregnancies. The intensity of pruritus and the laboratory alterations (increased serum bile salts and transaminases in almost all patients, hyperbilirubinaemia in 20% of patients) fluctuate during one pregnancy and also vary in subsequent affected pregnancies. This disease has no meaningful consequences for the mother; in contrast, it is associated with an increased risk of foetal distress, causing premature deliveries and stillbirths. Cholestasis of pregnancy has been recognized in most countries and ethnic groups but its prevalence is higher in Chile (14% of deliveries in 1975 and approximately 4% in 1995) and in Sweden than in other countries. The cause in unknown. Sex hormones, mainly oestrogens and progesterone, appear to be involved in its pathogenesis. An interplay between a genetic metabolic predisposition and some environmental factor(s) is apparently relevant. Clinical and experimental studies suggest that a marginal selenium deficiency could be a dietary pathogenic factor. Some drugs attenuate pruritus and improve maternal cholestasis, but not the foetal prognosis. Ursodeoxycholic acid (UDCA) administration provides a significant improvement in maternal pruritus and in the biochemical abnormalities, with no adverse effects in the mother or child. Recent clinical and experimental studies show that UDCA administration improves maternal disease and foetal prognosis without any detectable adverse effects.