1. INTRODUCTION AND RATIONALE The extreme increase of obesity in the last years had led to this study. There is no consensus about how to anaesthetise morbidly obese patients. The amounts of narcotics given during induction and maintenance of anaesthesia vary widely and rather depend on the anaesthetist than on the pharmacokinetics and dynamics in the morbidly obese patient (see figure 1 and 2). Despite the large range in induction doses (200-800 milligrams of Propofol, figure 1), the quality of induction of anaesthesia proved to be adequate in all cases. This can be explained by the central volume of distribution, which probably is the same in morbidly obese patients as in normal weight patients. This means that the induction dose of Propofol does not have to be adjusted in morbidly obese patients and that induction doses for non-obese patients can be applied, being 200 milligrams ( +/- 2.5 mg/kg). For maintenance of anaesthesia, however, pharmacokinetic parameters such as clearance and peripheral volume of distribution play an important role and are probably altered in morbidly obese patients.