Low-flow anaesthesia is a simple method of reducing the fresh gas flowrate for anaesthetic gases during inhalation anaesthesia. Sevoflurane hasa lower blood solubility which predicts a rapid uptake and elimination.Minimal degradation of isoflurane is related both to the stability of itsmolecule and to its rapid elimination from the body after itsadministration. Forty paediatric patients (2-10 years) were assigned intofour groups to inhale one of the two volatile anaesthetics; sevoflurane andisoflurane in high and low flow anaesthesia. A 10ml blood sample andurine sample were collected from each patient pre- and post-operativelyfor laboratory evaluation. Measurement of serum and urinary inorganicfluoride from the patients at 0, 12, 24 hour post induction of anaesthesia.the efficacy endpoint measures haemodynamic stability and improvementin recovery variables while safety endpoint measures hepatic and renallaboratory parameters, serum and urinary inorganic fluoride. The resultsof this study demonstrated that neither of sevoflurane or isoflurane hasdeleterious effects on liver or renal functions despite the transientelevation in serum and urinary inorganic fluoride ions with low flowsevoflurane anaesthesia. However, low-flow sevoflurane proved to besuperior to low-flow isoflurane anaesthesia in haemodynamic stabilityand faster recovery.