Abstract: The author studies the issues of legal protection of plants from hazardous organisms including alien species, whose invasions threaten biodiversity. Such a situation determines the complex research object - the relations emerging in the field of protection of plants from hazardous organisms. The problem of protection of plants from hazardous organisms is a complex problem, as it threatens crop plants as well as forests, and flora out of forests. Such relations are regulated at the international and national levels. 
The author uses a set of various methods, logical techniques, and means of cognition: general scientific and special legal including the formal legal and comparative legal research methods. At present, there’s a need in Russia for the development of the legislation guaranteeing an appropriate level of protection of crop plants from hazardous organisms, which are not quarantine objects. This problem can be regulated as in a fleshed-out law and together with the questions related to plant quarantine. The development and adoption of the law “On Flora” with a special attention given to the issues of the protection of out-of-forests flora, and their protection from hazardous organisms, are topical for the Russian Federation. The author suggests that, for the purpose of the increase of effectiveness of the struggle against hazardous organisms, the use of toxic substances should be allowed in forests if the use of other means is ineffective, and the potential risk of the use of toxic substances is lower than the expected useful effect.