We developed a 12-item bone marrow transplant subscale (BMTS) for the general Functional Assessment of Cancer Therapy (FACT) measure. The subscale combined with the FACT, (FACT-BMT) is a 47-item, valid and reliable measure of five dimensions of quality of life in bone marrow transplant patients. The three-step validation process involved the generation and selection of BMT-specific items and the testing of the overall measure. Items were selected from a list produced by seven oncology experts and 15 patients and were designed to assess content not represented in the general FACT items. A total of 182 patients completed the FACT-BMT at baseline, prior to BMT. An analysis measuring sensitivity to change was performed with 74 patients after transplantation and 60 patients over the three time-points of baseline, hospital discharge and 100 days. The FACT-BMT and all subscales were correlated, sensitivity to change was measured, and the internal consistency for each scale was calculated. Coefficients of reliability and validity ranged from 0.86 to 0.89 for the entire FACT-BMT and 0.54 to 0.63 for the BMTS. The BMTS was able to discriminate patients on the basis of performance status rating and also demonstrated sensitivity to change over time. The FACT-BMT has good psychometric properties for use in assessing quality of life in bone marrow transplant patients. The addition of the bone marrow transplant subscale to the general FACT measure makes it an excellent choice for use in BMT clinical trials.