A brief history of the regulation of medical device software within the United States is presented, along with a discussion of the reasoning that the US Food and Drug Administration (FDA) presents for modifying the requirements for software regulation from those previously used for hardware devices. The current regulatory status is discussed for the two categories of medical device software, software used within medical devices and software used to produce or test medical devices. The published FDA documents which determine the current environment for the regulation of software are summarized and discussed. The two types of medical device software are related to the two areas of FDA regulation, good manufacturing practices and permission to sell medical devices. The expected direction of future medical device software regulation, and its relationship to the European Economic Community (EEC) and international markets is discussed.