This study evaluated the efficacy of the relaxation response on the post-operative recovery of 27 cardiac surgery patients randomly assigned to one of two groups. Thirteen experimental group patients received educational information and practiced eliciting the relaxation response before and after surgery. The 14 patients in the control group received only information. Experimental and control groups were compared before and after surgery on both physiological and psychological recovery variables. There were no initial differences between experimental and control groups on demographic, physiological, and most psychological variables. The experimental group had lower incidence of postoperative supraventricular tachycardia (SVT) than the control group (p = .04) despite having had the same occurrence previously. Experimental and control groups did not significantly differ over the course of study on any other physiological variables. Patients practicing the relaxation response had greater decreases in psychological tension (p = .04) and anger (p = .04) than those who received only educational information. The decreases in psychological tension may have been a result of regression to the mean because the experimental group started with elevated tension relative to the control group (p = .04). We conclude that practicing the relaxation response before and after surgery may reduce SVT, tension, and anger.