Background:Postoperative shivering is one of the most common problems after general and local anesthesia. We compared the efficacy of low dose ketamine versus pethidine in controlling shivering after surgery.
Methods : In a double-blind randomized Clinical trial, 132 ASA I,II patients candidate for tonsillectomy were randomized to receive either pethidine and ketamine.  At the time of arrival to the recovery and after 30 minutes, the occurrence of chills and possible complications were evaluated and compared between the two groups.
Results : Two patients in the ketamin group (3%) experienced shivering while none of the patients in the pethidine group reported shivering (p>0.05). Other complications were more in the ketamin group (p<0.05)
Conclusion :  Ketamin and pethidine are equally effective in controlling postoperative shivering, but regarding the lower incidence of other complications, pethidine is still the first choice of treatment.