Using the example of substitution of peripheral blood stem cell (PBSC) collection to bone marrow harvest for autologous transplantation in cancer patients, our study attempts to illustrate how economic assessment, starting at an early stage of medical innovation, can influence the development and diffusion process of a new technological procedure whose optimal design has not yet been established. Two cost minimization studies comparing costs for obtaining a clinically reinfusable graft using bone marrow harvest or alternatively various protocols of PBSC collection contributed to a change in the French clinical standard for this procedure.