To analyse strategies, outcome and costs of immunogenetic marrow donor search 1012 patients were enrolled in a retrospective single centre study covering the period from January 1990 to December 1992. An HLA-compatible donor was identified for 562 of the patients (55.4%). Core family donor search (CFDS) provided a donor for 39%, extended family donor search (EFDS) for 6.4% and unrelated marrow donor search (UMDS) for 10% of the patients. During the period analysed, UMDS success rate increased from 13.3% to 47.8%, while mean search length decreased from 7.2 to 4.8 months. The percentage of donors from German registries rose from 5% in 1990 to 50% in 1993. Search length was dependent on patient's HLA phenotype frequency, but even for patients with frequencies as low as < 1:3 000 000 a donor was found in 5 of 24 cases. The mean costs (DM) per donor identified by CFDS, EFDS and UMDS were 2921, 19 172 and 24 036, respectively. Thus, CFDS is the utmost effective type of search. In view of the clinical outcome of BMT, EFDS remains a meaningful strategy and should not be replaced by UMDS despite its increasing success rate.