Bachelor thesis deals with the positive and negative effects of selected mushroom species on the human organism. The work is divided into two parts. The content of the first part is the history of mushrooms in human life, the systematic distribution of mushrooms, morphology, reproduction, growth, ecology and the chemical composition of mushrooms. The second part points to the negative effects of fungi that are spreading into intoxications. It also includes information on substances contained in fungi that have a positive effect on the human organism. At the end of the thesis are described selected types of mushrooms, including their use and effects.