Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems. WHO estimates traditional medicines, mostly plant drugs cater to the health needs of nearly 80% of world population. The aim was to study the influence of Trigonella foenum-graecum seed powder on the basic parameters of obesity induced by hight calorie diet. We included 40 male rats and divided them to 4 groups of 10 animals in each group. Normal rats (groups 1, 3) were fed by a standard chow, while the others (groups 1, 4) were fed with high-caloric diet during 14 weeks. From week 15 to 18, groups 2 and 4 were treated with Trigonella foenum-graecum seed powder (Fg). Liver function markers were estimated by biochemical analyzer Microlab 300 and commercial kits from Elitech diagnostic according to the standard protocols provided by manufacturers. The serotonin content was determined in brain using ion-exchange chromatography and fluorescence methods. We have shown that consumption of high-calorie diet leads to changes in food behavior and the development of obesity in rats. Treatment of obese rats with Trigonella foenum-graecum seed powder leads to normalisation of key physiological and biochemical parameters. Treatment with Fg significantly suppressed the increments of body weight, fat weight. Fg improved lipid levels. These results demonstrated the treatment effect of Trigonella foenum-graecum seed powder on the basic parameters of obesity induced by hight calorie diet.