The purpose of this study was to: (a) design and test an instrument to evaluate the incidence and severity of stressors associated with coronary bypass surgery and (b) assess the concordance between patient and nurse perceptions of such stressors. The patient sample consisted of 30 patients recovering without complications from coronary bypass surgery. Patients were white, primarily male and employed, one-third with graduate education, with a mean age of 54. The nurse sample consisted of 18 registered nurses with cardiosurgical nursing care experience. A 30-item stressor scale was developed: 27 items were derived from literature review and 3 from comments of cardiovascular clinical specialists. Stressfulness of each item was rated on a 5-point scale. A pilot study with seven patients provided information for initial scale refinement. Content validity of the scale has both theoretical and empirical support because of the varied sources used to obtain and validate relevant items for the tool. Homogeneity reliability of the scale was supported by high coefficient alphas. Based on severity of stress ratings, two-way analysis of variance indicated that the cardiothoracic nurses generally rated all items as significantly more stressful for coronary bypass patients than did the patients themselves. Comparisons used by the nurses and the patients in assigning stressfulness ratings are discussed.