Recently, five cases of hepatic angiosarcoma were found in Louisville. All of the patients had worked in a plant engaged in the production of polyvinyl chloride (PVC) from vinyl chloride. A systematic health surveillance program was instituted to detect existing liver damage or angiosarcoma and to find early signs of developing liver damage. A protocol was devised that began with on-site phlebotomies done in the plant and progressed to sophisticated hospital studies, if important abnormalities were found. All of the 1,183 employees of the plant were tested. Two new cases of hepatic angiosarcoma and three cases of portal fibrosis were discovered by this program at the initial screening. It is hoped that continuous health monitoring will aid detection of liver abnormalities while still in a reversible or curable state. (JAMA230:64-68, 1974)