Introduction & Objective: Low flow anesthesia technique in which the flow fresh gas is lower than minute volume of the patient results in improvement in the patient’s care such as reduction of operative hypothermia, reduction of postoperative shivering and leads to an increase in economical and enviornmental interests. The goal of the study was to investigate the patients’ operative hemodynamic variations using the high and low flow anesthesia techniques. Materials & Methods: This prospective, clincal and single blind study was carried out in Tbriz Emam Khomeini Hospital in 1384. In this study 97 patients in ASA class I or II after routine induction of G.A, during maintenance of anesthesia were randomly divided in two groups group I (high flow anesthesia) and group II (low flow anesthesia). For all patients ECG, HR, SPO2, BP, B.T, ETCO2 and inspiratory, expiratory percentage of O2, N2O, halothane, postoprative shievring and duration of oprations were recorded. 46 patients underwent high flow anesthesia and 51 patients underwent low flow anesthesia. Results: The average blood pressure in group I was as follow: preoperative, systol=13820 mmHg and diastol=7815 mmHg, intraoperative, systol=10531 mmHg and diastol=6410 mmHg and in recovery systol=11615 mmHg and diastol=7013 mmHg. In group II who had low flow anesthesia the blood pressure was found to be systol=13922 mmHg and diastol=7922 mmHg preoperative, systol=12221 mmHg and diastol=7517 mmHg intraoperative and systol=11815 mmHg and diastol=7717 mmHg in recovery. The differences in blood pressure in both group were statiscally significant (p=0.01). The average heart rate in group I was 9018 beat/min preoperative, 7014 intraoperative and 126 in recovery. The avrage heart rate in group II was 87.921 preoperative, 8616 intraoperative and 10417 in recovery. The differences were statiscally significant but there was no significant difference between the two groups with regard to sex, age and weight. Conclusion: Maintenance of anesthesia with low flow anesthesia gasses maintains more hemodynamic condition during operation.