On August 1, 2014, the Food and Drug Administration (FDA) released draft guidance that would exempt from premarket 510(k) review many low-risk medical devices--including certain mobile applications that can convert a cell phone into a medical device, such as a thermometer or a stethoscope. Although the guidance is not yet legally enforceable, the FDA also announced its intention not to enforce compliance with premarket review requirements for these devices and noted that it did not expect manufacturers to submit 510(k)s for these devices prior to adoption of a final rule or order. The FDA's recognition that these devices are sufficiently well understood and do not present risks that require premarket review to ensure their safety and effectiveness--and its corollary decision to exercise enforcement discretion as to these devices--eases the regulatory burden on medical application developers and expands opportunities for continued development and dissemination of important mobile tools for improving patient care and physician practice.