An anaesthetic nurse intervention was performed in order to evaluate the effects of extended preoperative information, given by anaesthetic nurses, on perioperative stress in patients operated on for breast cancer or total hip replacement (THR). Forty-six consecutive patients scheduled for surgery for breast cancer, and 55 for THR, were randomized into two groups which were given different modes of preoperative information. Patients in the control group were informed about pre-and postoperative routines by a ward nurse. Patients in the intervention group were given extended formalized information by an anaesthetic nurse. Wilcoxon rank sum test was used to show relations between variables. There were no significant differences between the intervention group and control group for patients with breast cancer or for patients with THR. Breast cancer patients in the intervention group were significantly more anxious than THR patients in the intervention group (P<0.01). Breast cancer patients in the intervention group showed the highest anxiety scores on the Hospital Anxiety and Depression Scale (HADS) scale on the day of surgery. This information may reflect an increased level of anxiety due to the extended information given preoperatively. The information may thus have had a negative effect on breast cancer patients, resulting in an increased state of anxiety. The result indicates a need for individualized modes of information to provide a proper balance between enough and too much information. © 1998 Harcourt Brace & Co. Ltd.