Personnel involved in supportive care of bone marrow transplant (BMT) patients include fellows (F), medical house-staff (HS), nurse practitioners (NP), physician assistants (PA), and moonlighting physicians (MP). We have obtained surveys from 108 American and Canadian transplant centers on the composition of inpatient support teams. Eighty-seven percent of institutions responding to the survey were university-based programs. Eighty-eight percent of the centers performed both allogeneic and autologous transplants, and 60% performed unrelated donor grafts. The mean number of transplants performed annually at each center was 101 (range 4-515). For daytime coverage, the percent of programs involving F, HS, NP, PA, or MP was 57, 50, 35, 25, and 0%, respectively, and for nighttime coverage, the composition was 50, 56, 7, 6, and 13%, respectively. Medical HS were incorporated into the care of BMT patients at some level in 93% of the programs. Involvement by HS included full 24-hour coverage (44%), full nighttime coverage (8%), stat coverage (18%), and code blue only coverage (21%). HS involvement was similar in small and large transplant programs. HS were more involved in university-based programs. Programs on the East Coast had more HS involvement, with 54% of the programs reporting full 24-hour coverage by HS compared with 32% of the programs in the Pacific region. Coverage of transplant patients varies throughout the country, and nonphysician providers are often used. HS are more active in university-based programs, and their role is similar in both large and small programs.