The relationship between fulminant viral hepatitis (FVH) and pregnancy was compared in Algeria and France. This comparison was based on the study of 22 Algerian and 77 French pregnant and non-pregnant women, aged 15 to 49 years, consecutively admitted for FVH to the Centre Hospitalier Universitaire, Constantine, Algeria, or to Hôpital Beaujon, Clichy, France. The observed and expected (calculated from demographic data) percentage of pregnant women was significantly different among the Algerian patients with FVH (45.5% v. 24.9%, P less than 0.03), but not among the French patients (3.9% v. 5.8%). Hepatitis A was the cause of FVH in none of the Algerian patients, but in eight French patients, none of whom was pregnant. Hepatitis B was the cause of FVH in one non-pregnant Algerian patient and in 49 French patients, two of whom (4.1%) were pregnant. Hepatitis non-A, non-B was the cause of FVH in 21 Algerian patients, ten of whom (47.6%, a percentage significantly higher than expected, P less than 0.04) were pregnant, and in 19 French patients, one of whom (5.3%, a percentage similar to that expected) was pregnant. In conclusion, (1) there is a relationship between FVH and pregnancy in Algeria, but not in France, and (2) this difference is mainly or exclusively attributable to infection with a non-A, non-B virus affecting the Algerian population, but which is much less common or absent in France.