In this study, the mitotic index (MI) and Sister Cromatid Exchange (SCE) levels were investigated to identify the mutagenic and carcinogenic effects of sevoflurane (sevorane). The data of 20 patients in ASA I-II were studied. All of the patients received an anaesthesia induction with anaesthesia mask and 'tidal volume method. 8 % sevoflurane in 100 % oksigen was used to the induction of anaesthesia and 0.1 mg/kg vecuronium for neuromuscular block and intratracheal intubation. Anaesthesia continued with 2-2.5 sevoflurane, in 60 % N2O and 40 % O2 . Three mL venous blood samples taken before (as controls) 60 minutes, 24 hours and 5 days after the sevoflurane induction, were examined according to the periferic blood culture assay with conventional cytogenetic methods. On the metaphase plaques which obtained in this way, the levels of MI and SCE were examined. As a result, a significant decrease of MI has been found in the test objects at the first 60 minutes of sevoflurane anaesthesia compared to controls (p<0.001). But this depression was smaller after 24 hours (p<0.01) and reversible after 5 days (p>0.05). SCE increased significantly at the first 60 minutes of anaesthesia (p<0.001) was also smaller after 24 hours (p<0.01) and returned to normal levels after 5 days (p>0.05). As conclusion; It has been revealed the effects of sevoflurane on cellular replication and on DNA at the cellular level were repaired in a short period of time. Thus, it has been suggested that sevoflurane had no permanent effect on genetic material of healthy individuals.