These are comments written by the Governing Council of the Organization for Human Brain Mapping (OHBM), the primary international organization dedicated to neuroimaging research. The purpose of these comments is to identify and frame issues concerning data sharing within the neuroimaging community. Data sharing has become an important issue in most fields of science. The neuroimaging community is no exception, and it clearly perceives potential benefits in such efforts, as have been realized in other fields such as genomics. At the same time, such efforts can be costly (both in time and expense), and there are important factors that differentiate brain imaging from other fields and that pose specific challenges to the generation of useful neuroimaging databases. These include the rapid pace of change in brain imaging technologies; the complexity of the variables that must be specified to meaningfully interpret the results (such as the method of image acquisition, behavioral design, and subject characteristics); and concerns about participant confidentiality. These issues are outlined with the goal of framing and promoting a public discussion of the benefits and risks of data sharing, which can inform the field of neuroimaging as well as others that face similar challenges.