The Marine Mammal Protection Act (MMPA) was last reauthorized in 1994. The MMPAs authorization of appropriations expired at the end of FY1999. At issue for Congress are the terms and conditions of provisions designed to reauthorize and amend the MMPA to address a variety of concerns relating to marine mammal management. In the 109th Congress, the House passed a bill to reauthorize and amend the MMPA, but no further action was taken on this measure. The 110th Congress may again consider measures to amend and reauthorize the MMPA as well as bills to address specific marine mammal regulatory and management issues. Several issues that may arise in reauthorization relate to modifying management of the interactions between marine mammals and commercial fishing operations. Other concerns relate to marine mammals in captivity and subsistence use of marine mammals by Native Americans. Additional issues include providing for trade in marine mammal products, managing robust marine mammal stocks, understanding the effect of noise on marine mammals, fostering international cooperation, regulating large incidental takes, modifying the scientific research permit process, improving agency compliance with MMPA deadlines, facilitating marine mammal research by federal scientists, dealing with harassment of marine mammals, considering a directed research program, and appropriating adequate funding for federal agency programs. While some of these issues could be addressed administratively, in regulations proposed and promulgated by the National Marine Fisheries Service, the U.S. Fish and Wildlife Service, or the USDA Animal and Plant Health Inspection Service, others likely would require statutory changes. Most potential participants in the reauthorization debate anticipate extended negotiations on some of these issues. Although the authorization for appropriations expired at the end of FY1999, the MMPA itself did not expire. Eventually, however, an extension of funding authority may need to be considered to continue federal program operations. Most of the issues associated with this law are not time- sensitive, and a number of oversight hearings have been held to increase understanding of various issues, positions, and possibilities.