Comparison of Ondansetron and Lidocaine in Preventing of Propofol Injection Pain This study was examined to compare the efficiency of propofol injection pain prevention with the effect of ondansetron and lidocaine. The study were included 75 adult patients were divided into three groups (n=25). The turniquet was applied on the forearm. Patients in Group I received 2 cc (4 mg) ondansetron, in Group II received 2 cc (2%) lidocaine and in Group III received 2 cc of iv 0.9% saline. After 30 seconds, turniquet was released. One fourth of total dose (2.5 mg/kg) was injected in 4 sec. Then the intensity of pain and arm withdrawn was observed. Than three fourth of propofol was given. Pretreatment with ondansetron and lidocaine significantly reduced the incidence of propofol pain comparing with the placebo (48%, 36 and 96 respectively) (p