Edible insects have gained the status of highly nutritious food with high protein and fat content. However, nutritional value of insects is not constant. It could be affected by species, developmental stage, rearing technology, nutrition or sex. This study's goal is to determine the protein and fat contents of three edible beetle species (giant mealworm - larvae of Zophobas morio, mealworm - larvae of Tenebrio molitor and, lesser mealworm - larvae of Alphitobius diaperinus) bred in the Czech Republic. Based on the obtained results, all investigated species could be considered as a reasonable source of lipids and two of them (mealworm and lesser mealworm) are also an excellent source of protein. Crude protein content of mealworm (630 g. kg-1 DM) was found to be higher than in other studies. The investigated species of lesser mealworm contained 600 g of crude protein/kg DM, which was equal to the results of other authors. Most authors report a higher content of nitrogen in the giant mealworm than were the values measured by this experiment (390 g.kg-1 DM). The lipid content in the tested samples was found in a range of 170 - 390 g.kg-1 DM. The highest lipid content was found in the larvae of giant mealworm and the lowest lipid content was found in the larvae of mealworm. The determined fat content of lesser mealworms was 290 g.kg-1. The fatty acid profiles of all samples were also determined.