The scientific and public health benefits of mandatory data-sharing mechanisms must be actively demonstrated. To this end, we manually reviewed 2724 data access requests approved between June 2007 and August 2010 through the U.S. National Center for Biotechnology Information database of genotypes and phenotypes (dbGaP). Our analysis demonstrates that dbGaP enables a wide range of secondary research by investigators from academic, governmental, and nonprofit and for-profit institutions in the United States and abroad. However, limitations in public reporting preclude the tracing of outcomes from secondary research to longer-term translational benefit.