Abstract
Althesin anaesthesia alone had no significant effect on plasma cortisol concentration. When Althesin induction was followed by maintenance with N2O and halothane there was a statistically insignificant fall, but with N2O, pancuronium and I.P.P.V there was a tendency for plasma cortisol concentrations to rise. This, too, was statistically not significant. A significant elevation in the mean plasma cortisol concentration was only found in patients during abdominal surgery.