Background: Succinylcholine is drug muscle relaxant the only depolarizing current can also be used in clinical. Objectives: The current study assessed the intubation condition and side effects of different doses of succinylcholine. Subjects and method: In a randomized, double blind trial, 90 patients were divided into 3 groups. 1, 1.5 or 2 mg/kg succinylcholine was added with Fentanyl and Thiopental for induction in group I, II and III, respectively. A rapid induction and postoperative myalgia were evaluated. Results: Fasciculation time as well as myalgia increased significantly by the doses. Intubation conditions were better in group II and III. Increase of kalemia was seen in all groups, but most significantly in group III (3,7 \xb1 0,3 vs 3,3 \xb1 0,2, p<0,05). Conclusion: 1, 1.5 or 2 mg/kg succinylcholine equally provided acceptable intubation condition. Succinylcholine 2 mg/kg induced more fasciculation, myalgia and increase of kalemia.