The 1977 Bureau of Mines mineral investigation program in the National Petroleum Reserve-Alaska (NPR-A) was designed to make a preliminary evaluation of known and reported mineral showings, a followup on the U.S. Geological Survey's 1977 regional geochemical results, and sample color anomalies--those due to oxidation of iron. Eighteen separate areas were examined during the 1977 field season. Significant mineralization was found at only one site, the Drenchwater Creek Area, where concentrations of base metal sulfides occur in and near outcrop. The zinc-lead-silver bearing zone has been traced along strike and is at least 6,500 feet long and may possibly extend more than 10,000 feet. Minor mineralization has been found at other sites. These include fluorite at Mount Bupto, chromite at Siniktanneyak Mountain, and barite nodules near Safari Creek.