Biological ways of control (augmentative, classic, conservative) fall into nonchemical methods and are used as an alternative to chemical pesticides used to control harmful organisms in integrated and ecological systems of agricultural production. Biological plant protection includes control of harmful insects by use of natural enemies (predators, parasitoids), other beneficial organisms, and microbiological insecticides based on viruses, bacteria, fungus, and nematodes. It is possible to use biological protection to control all harmful organisms in orchards, vineyards, controlled and storage areas, and in nature. Due to them being easier to check on beneficial insects are most often released and used in controlled areas. Controlling beneficial fauna is harder to carry out in nature. On Croatian market Colić-trade d.o.o. and Zeleni hit d.o.o. are companies that offer a wide assortment of products for biological control of harmful insect, produced by a well-known Dutch company Koppert. Beneficial organisms maintain stability and balance of an agroecosystem by attacking, infecting or feeding on harmful insects and thus keep them under the ecological damage threshold. Biological control has many advantages over chemical control, e.g. it prevents accumulation of chemical substances in the ground, water, and air, it leaves no residues in plant and animal products, it doesn’t harm nontargeted organisms, animals, and man, it doesn’t cause phytotoxic damage to plants, it excludes the problem of development of pest resistance over time, and it can contribute to significant reduction to emission of greenhouse gases. Farmers are repelled from using biological protection by unavailability and the small number of registered products that are available on Croatian market, higher prices, difficulty of application, slower performance of preparation, and required knowledge of application which is based on newer scientific research.