A causal link has been proposed between presumed consent (PC) and increased donation; we hypothesized that too much heterogeneity exists in transplantation systems to support this inference. We explored variations in PC implementation and other potential factors affecting donation rates. In-depth interviews were performed with senior transplant physicians from 13 European PC countries. Donation was always discussed with family and would not proceed against objections. Country-specific, nonconsent factors were identified that could explain differences in donation rates. Because the process of donation in PC countries does not differ dramatically from the process in non-PC countries, it seems unlikely that PC alone increases donation rates.