Three North Sea fields with temperatures greater than 140 degreesC have lead sulphide (PbS) and zinc sulphide (ZnS) scales. Conventional inhibitors cannot control these scales and their removal by chemical means can result in formation of hydrogen sulfide (H2S). The full-length paper describes development of a novel scale-inhibitor package as well as its successful application in these fields. Mechanical and chemical removal also are discussed as alternatives to inhibition.