purpose: to study the safety and efficiency of two anesthetic blockages in hemorroidectomy and the effect of clonidine on analgesia. methods: 80 patients were studied, randomly divided into four groups: l (n=19)- peridural with a 0,75% ropivacaine; 2 (n=21)-peridural with a 0,75% ropivacaine and 150 μg of clonidine; 3 (n=19)- subarachnoid with a 0,5% bupivacaine; 4 (n=21)- subarachnoid with a 0,5% bupivacaine and 50 μg of clonidine. the intensity of pain was evaluated by the visual analogical scale 8, 12 and 24 hours after surgery. the use of vasoconstrictors on the transoperatory and the amount of analgesics within the 24 hours were registered. results: the intensity of pain, 8 hours after surgery, was lesser on group 4, and much lesser on group 4 comparing with groups 1 and 2, 12 hours (p=0,022; p=0,001) and 24 hours (p=0,03; p=0,003). the frequency of vasoconstrictors usage on the transoperatory and the analgesics on the post-operatory showed no difference among the groups. there were no anesthetic complications. conclusions: the subarachnoid anesthesia with a 0,5% bupivacaine with clonidine, showed better analgesia comparing with the peridural anesthesia with a 0,75% ropivacaine with or without clonidine, however all were safe and efficient. the clonidine aided on the decreasing of pain when subarachnoid anesthesia was used.