Sevoflurane (Fluromethyl 1,1,1,3,3,3, Hexafluoro isopropyl ether) is one of the newly introduced inhalational Anaesthesia. It is considered as a rapid acting and potent inhalation anaesthetic agent. It is metabolized in the body into non-toxic substances. It also has a rapid uptake and elimination rate due to its low blood gas partition coefficient, which approaches that of nitrous oxide. Interest in sevoflurane has increased with the recent emphasis for out patient surgery because it has a mild ethereal odor and low solubility in blood; lipid; and tissues. So, it is suggested as being anaesthetic of the future. This study is designed to illustrate the histological and the clinical effects of sevoflurane in comparison with isoflurane as a common inhalational anaesthetic agent, regarding the haemodynamic, hepatic and renal effects. The clinical study included 80 adult persons of both sexes, during surgical operations. The patients were divided into 2 groups, 40 persons each. Group I: received sevoflurane and group II: received isoflurane. Routine examinations; investigations; Liver and renal function tests were done just before induction and after 2 hours; 4 hours; 24 hours and 7 days of recovery. The experimental study was done on 90 rats of both sexes. They were divided into 3 groups: 30 rats each. Group (A): control group, group (B): Anaesthetized with sevoflurane and group (C): Anaesthetized with isoflurane. Each group was subdivided into 2 subgroups, 15 rats. The 1st subgroup was sacrificed after 24 hours of exposure. The 2nd subgroup was sacrificed after 7 days from the start of exposure. The rats were sacrificed and their blood was investigated. Liver and kidney structure were evaluated histologically and histochemically. Our results revealed that, sevoflurane and isoflurane had non-significant post-operative clinical manifestations and non-significant changes on the liver or kidney function tests. Histological examination of liver revealed normal hepatocytes and mild congestion in blood sinusoids and central veins in sevoflurane group. While, liver sections in isoflurane group showed more congestion, dilatation and cellular infiltration. . Histological examination of the kidney revealed no changes in the sevoflurane group. In contrast, isoflurane group had congestion and cellular infiltration of renal parenchyma. All changes almost completely disappeared after seven days of recovery. Histochemical results revealed significant decrease in PAS positive material and succinic dehydrogenase enzyme activity in hepatocytes and renal tubules, mainly in isoflurane than sevoflurane groups. While, acid and alkaline phosphatase enzymes activity showed non-significant decrease in both drugs. All changes were non- significant after seven days of recovery. This study proved that the sevoflurane had no harmful effect and can be considered as a safe inhalational drug.