A growing number of obese people throughout the world have become a health-economic problem. Obesity and overweight are significant risk factors causing increased morbidity and mortality in obese people. Nevertheless, a marked improvement in the prognosis is achieved by a 5–10 % decrease in body weight 1). Since 1 July 2002, two preparations for long-term therapy of obesity have been registered in the Czech Republic: Xenical (orlistat) and Meridia (sibutramin). Long-term randomized double-blind studies have shown that a decrease of 4.4 kg in weight within a year is achieved by 10 mg sibutramin administration, a decrease of 3.2–6.4 kg in weight within a year is achieved by 15 mg sibutramin administration, a decrease of 7.4–9.1 kg in weight within a year is achieved by orlistat administration, and placebo administration causes changes in weight ranging from -6.5 kg to +0.94 kg. A cost-to-effectiveness comparison has revealed that in one year the direct costs (ORC) of a decrease in body weight by 1 kg after deduction of the placebo effect make 9 817 CZK to 22 078 CZK (the supplementary payment of the patient being 2698 CZK to 7722 CZK) in sibutramin treatment, and 9101 CZK to 13 085 CZK (the supplementary payment of the patient being 632 CZK to 909 CZK) in orlistat treatment.

        Key words: obesity – sibutramin – orlistat – effectiveness – costs