We describe the experience of the occupational health centre at the Sarnia Division of Dow Chemical Canada prior to, during and after a work stoppage of seven months duration. A descriptive analysis was performed of the occupational health case load during the work stoppage compared to the same period one year earlier. Total visits as well as those for dermatologic, upper respiratory, musculoskeletal and those associated with a non-occupationally related situation (e.g., sunburn) exceeded normal frequencies during the first ten weeks of the work stoppage. In particular, there was a peak number of visits during the first two weeks when a 'lock-in' prevented employees from visiting their own physicians except for emergency situations. In the Discussion section, recommendations are outlined to lessen the chance of adverse health effects in workers responsible for operating a chemical plant during a work stoppage.