This study examined the effect of preoperative roommate assignment on the preoperative anxiety and postoperative recovery of 27 male coronary-bypass patients. Patients were assigned preoperatively to a roommate who was either similar or dissimilar in his surgical status (preoperative vs. postoperative, respectively) and either similar or dissimilar in his type of operation (cardiac vs. noncardiac, respectively). The results indicated that the similarity/dissimilarity of a roommate's surgical status exerted important effects. Specifically, patients who before their operations had a postoperative roommate were less anxious preoperatively, were more ambulatory postoperatively, and were released more quickly from the hospital than patients who before their operations had a preoperative roommate. In contrast, the similarity/dissimilarity of the roommate's type of operation exerted no significant effects either separately or in interaction with the similarity of the roommate's surgical status. Theoretical implications, possible mechanisms, and practical implications for hospital policy are discussed.