In a comparative study of the effect of individual and group preoperative teaching on a postoperative ventilatory function, length of hospitalization, postoperative need for analgesia, and length of learning time, group teaching was found to be as effective as and more efficient than individual teaching. When age, smoking history, and site of incision were included as classification variables, age and smoking history were found to not alter the effectiveness of either method of preoperative teaching, but site of incision did interact in a significant way with the teaching method; subjects who received group instruction and who had, previous incisions had a shorter hospitalization than the same group receiving individual instruction. Age and smoking history did not affect postoperative ventilatory function and need for analgesia, but site of incision did. Age was found to affect length of hospital stay and postoperative need for analgesics; older subjects had, a longer stay and received fewer analgesics. Subjects of the study—all adult surgical patients who met certain criteria during a 15-week period in one general hospital (N = 351)—were randomly assigned by weeks to group or individual teaching. Thirty-one registered nurses from the surgical unit did the preoperative teaching.