Many health care systems include programs that allow patients in exceptional circumstances to access medical interventions of as yet unproven benefit. In this article we consider the ethical justifications for—and demands on—these special access programs (SAPs). SAPs have a compassionate basis: They give patients with limited options the opportunity to try interventions that are not yet approved by standard regulatory processes. But while they signal that health care systems can and will respond to individual suffering, SAPs have several disadvantages, including (...) the potential to undermine regulatory and knowledge-generation structures that constitute significant public goods. The “balance” between these considerations depends in part on how broadly SAPs are used, but also on whether SAPs can be made to contribute to the generation of knowledge about the effects of health interventions. We argue that patients should usually be required to contribute outcome data while using SAPs. (shrink)