This survey investigated allogeneic bone marrow transplantation (BMT) policy in European BMT units by questionnaire, in relation to pre-transplant liver disease. It also assessed diagnostic standards for viral hepatitis infections and their prevalence in BMT candidates. Sixty-three EBMT centers from 22 countries participated in the survey. Median pre-transplant prevalences of HBsAg and anti-HCV positivity were 3.5% (range 0-15%) and 5% (range 0-45%), respectively. Forty-six (73%) centers adopt the policy of cancelling or postponing BMT in patients with ALT abnormalities but in four of these centers, BMT is not delayed when progressive disease or acute leukemia is present. In 17 institutions (27%) BMT was reported to be carried out irrespective of transaminase values. Data on fatal post-BMT liver disease were provided by 45 centers. The overall mortality rate for liver failure was 4.5% (258 of 5788) with no differences between centers performing or not performing BMT in cases of ALT elevation. These results indicate that there is strong concern in most European BMT units about performing BMT in the presence of ALT elevation and prospective studies on its real impact on fatal post-BMT liver disease should be conducted.