We assessed the effect of small clonidine doses on anxiolysis, analgesia, and hemodynamic stability in patients undergoing abdominal hysterectomy. A total of 61 patients, ASA status I-II, were randomly assigned to receive either oral clonidine 100 microg (n = 29) or placebo (n = 32) before surgery and 24 h after surgery. The use of clonidine resulted in anxiolysis and analgesia throughout the 72 h after surgery, although the subjects who received clonidine were sleepier than the control group for the first 6 h after surgery. The number needed to treat was 3 (95% confidence interval [CI], 1.72-9.42) to prevent intense anxiety in patients with moderate to intense postoperative pain, compared with 40 (95% CI, 18.79-99.68) in the absence of pain or with mild pain. In the treated patients, 68% had an average heart rate less than 70 bpm during surgery, compared with 21.40% in the placebo group (number needed to treat, 2; 95% CI, 1.29-2.80). The clonidine patients required small ropivacaine doses during the surgery but not less morphine by patient-controlled analgesia. A clinically relevant anxiolytic effect was found in patients who received oral clonidine in the perioperative period, and this suggests that clonidine might be a useful therapeutic alternative to other preoperative sedatives.