Abstract: On February 26, 1984, four employees began cleaning the inside of a copper plating tank with methylene chloride soaked rags. The tank was empty. It's dimensions were 5 feet deep by 8 feet wide by 12 feet long. Approximately 2 gallons of methylene chloride were brought into the tank in one or two plastic buckets. Each employee, using a rag with methylene chloride, started wiping down a wall of the tank. After several minutes the men became dizzy, passed out, and dropped to the floor of the tank. Two plant rescue personnel arrived at the tank after a passerby saw the men unconscious in the tank. The two rescue personnel attempted to remove the men from the tank but were unsuccessful until fire dept personnel arrived with additional gear. The four men were hospitalized for several days and fully recovered. One rescue person felt sick after helping the fire department remove the victims and was also taken to the hospital for examination and release.