The aim of this study is to find out which of the uses – propofol or thiopental – in the anaesthetic induction in the events of laparoscopic cholecystectomy could have a more positive effect on oxidative stress and to investigate the relation between the events’ haemodynamic parameter variables and oxidative stress. Planned as randomized and prospective, our study was carried out with 60 patients in the operating theatre of Ankara Atatürk Training and Research Hospital. Patients were randomly divided into two equal groups. In the anesthetic induction of the patients, in Group 1 thiopental 4-7 mg/kg iv and in Group 2 propofol 2-3 mg/kg iv were used. The other drugs used were the same. Hemodynamic data were recorded at designated times. To measure serum thiol-disulphide, TAS (total antioxidant status), TOS (total oxidant status), PON1 (paraoxonase) and ARES (arylesterase) levels, blood was drawn from the patients two times – one being before the general anesthesia induction and the other in the recovery room.While the thiol levels that include TOS, ARES and SH are affected similarly in both groups, TAS levels were found to be unchanged in thiopental group but to increase in propofol group, and PON1 level was found to be unchanged in propofol group and to decrease in thiopental group. Moreover, when the patients whose anesthesia ended in the morning and in the afternoon were studied within themselves in terms of changes in the oxidative stress parameters before and after operation, determination of the fact that there was a meaningful increase in the post-operative TAS values of patients whose anesthesia ended in the morning and that there was a more meaningful decrease in post-operative PON1, ARES and thiol levels in patients whose anesthesia ended in the afternoon gave rise to the thought that oxidative stress was higher in the afternoon. In our study, a positive correlation between post-operative TAS, PON1 and ARES and general blood pressure values; between post-operative TOS values and KAH values in induction; between ETCO2 values on the fifth minute of the operation and TOS values; between ARES value and post-extubation SpO2 and a negative correlation between PON1 and ARES values and KAH values were determined. In our study, we concluded that propofol would be a preferable iv anesthetic agent as it caused an increase in TAS level. Furthermore, in our study it was decided that we needed to avoid conditions such as hypertension, uncontrolled hypotension, tachycardia, hypercapnia, and hypoxia to reduce the oxidative stress.