Carpal tunnel syndrome (CTS) was evaluated among workers in the assembly department of a window hardware manufacturing facility. The facility manufactured window balance systems from stamped, rolled aluminum or vinyl. Twenty eight female employees on five assembly lines were studied in relation to CTS, Guyon's canal syndrome, and tendinitis. The annual incidence rate for the disorders was 23.4 per 200,000 hours worked. Repetitiveness, strongly associated with CTS and other cumulative trauma disorders, was assessed through cycle or subcycle time and manual manipulations. Muscular exertion (force) was evaluated subjectively except for two tasks in which a calibrated force gauge was used. All twelve assembly jobs involved CTS risk factors; eight were highly repetitive. Extreme postures were also involved in all of the jobs in the assembly department. A job rotation policy in effect at the time of the study was unsuccessful because the jobs involved similar risk factors. The author recommends that the jobs classified as highly repetitive be shared by more workers or slowed down. Relocation of parts, use of appropriately designed holding bins, and product transporting conveyors are recommended to correct extreme postures. Two specially designed hand tools could be improved by addition of longer, larger, padded handles and a different angle. Better parts design and quality control are also recommended to facilitate assembly.