Abstract: The author reported the result of an investigation of the plywood workshop of a wood-frame clock factory in Yantai city carried out in 1978. Among 35 workers examined, theta were 13 cases (37.1%)of contact dermatitis. 12 of them were workers applying urea-formaldehyde, and 1 patient was a worker making the resin. Most workers examined had irritant symptoms of upper respiratory tract. Based on the data of investigation and the result of patch test, the author considered formal-dehyde is urea-formaldehyde resin to be the main causative agent. Finally the author put forward some preventive measures.