At present biologists are finding great attention to the study of parasitocenosis. However such research is carried out mainly in the agricultural and producers animals. Amphibians and reptiles are poorly understood, as the low value species for the human. In general parasitic cenosis of amphibians in Khanty-Mansiysk Autonomous Area have not been investigated. The article discusses the common helminth infection of internal organs of moor frog of Middle Ob. Investigations were carried out on the Khanty-Mansiysk Autonomous Area-Ugra in May-June 2016 in the environs of Yugan village, in the Surgut city and in the surrounding of Nizhnevartovsk city. Were studied 123 individuals of R. arvalis with application of incomplete helminthological method. Were defined generally accepted indicators of the parasite population. Were determined of high extent of infestation of the lungs and gastrointestinal tract of moor frog, whereas the liver, heart and kidneys faintly contaminated with worms, and in the spleen and the gonads parasitic worms are not revealed. Significant differences in the extensiveness of worms infestation between populations of moor frog on the territory of Khanty-Mansiysk Autonomous Area -Ugra is not established. Despite the fact that in the Surgut city in index of abundance of worms of moor frog was highest, compared with the control area (the environs of Yugan village). The reason for this may be poor species composition of helminths in the city and the for lack of competition between species. Sex differences in worm invasion of frogs have been exposed.