Abstract: While sewing children's dresses and sportswear, Employees #1 through #6, machine operators and general laborers in a sewing plant, began to suffer headaches, nausea, and weakness. At the local hospital, examination findings were negative and the employees were sent home. Investigation of the incident revealed that the lpg-fired boiler was probably the emission source of carbon monoxide. The fumes may have entered the work area through openings around the roof eaves on the south (rear) side of the building. The investigation, including atmospheric testing and medical examinations, did not reveal or establish overexposure to any toxic substance. Reconstructing the conditions existing at the time of the incident was not possible.