Glucosinolates are bioactive substances found in cruciferous plants (Brassicaceae). When injury to the plant tissue occurs, the glucosinolate-mirosynase system is activated and acts as a defensive mechanism of the plant. Degradation products such as isothiocyanates may be toxic for certain pathogens and pests. On the contrary, hydrolysis products may have some positive effects on human health, because they exhibit may reduce the risk of certain cancers and act as antioxidant. They also prevent cardio-vascular diseases and diabetes. Glucosinolates also play a role in controlling various types of weeds, which can contribute to reduced the use of synthetic herbicides. The level of glucosinolates in plants is influenced by several environmental factors. In order to achive the highest production of bioactive substances, these factors must be taken into account in the production of cruciferous plants. The content of glucosinolates in cruciferous plants is influenced by species and variety, exposure to pests and pathogens, age or delevelopment phase of the plant, and competitiveness with other plant species. The concentration of glucosinolates depends also on various climate factors, such as temperature, accesibility of water, sunlight, season and pollutants. The level of glucosinolates in plants is furthermore affected by the availability of nutrients and fertilization, irrigation, cultivation methods and some other agronomic practices.