The processes of change associated with smoking cessation were examined for 213 smokers and recent exsmokers who were scheduled for cardiac catheterization and compared to the processes reported by a sample of 180 nonmedical smokers and exsmokers. Subjects were classified into one of three stages of change depending on their readiness to quit smoking: precontemplation, contemplation, and action. The cardiac sample employed the processes of change more frequently than the nonmedical sample in all stages, but the functional relationship between the stages and processes of change was generally similar for the two groups. The hierarchical structure of the processes of change also was similar for both groups. Differences between the two samples in the use of the processes of change are discussed. These results are the first to support the validity of the stages and processes-of-change model of smoking cessation in a population experiencing severe illness.