This article presents data about variability of morphological features of Rosa canina L. fruits. The dog-rose (R. canina) is a useful medical and ornamental plant. It is ecologically flexible and grows in a wide diapason of ecological conditions, more specifically, in forest, forest steppe and steppe environmental areas. Morphological parameters of a dog-rose fruits are pretty changeable depending on environmental conditions, that is why there is a question of current interest in studying the variability of carpological parameters and the diapason of modifiability of a dog-rose. The objective of the research is the peculiar properties of reproductive sphere of R. canina. The subject of the research is variability of morphological features of R. canina fruits in the environment of 3 types of ecotopes in theNorthern Black Sea region. The work materials are herbarium and the results of measurements of fruits of 20 R. canina individuals on 20 test areas in urbanized ecotopes (the parks of Mykolaiv city), in ecotopes as a part of agricultural landscapes (in the vicinity of Shevchenkove village, Mykolaiv region), and in ecotopes with small anthropogenic transformation of flora (Pryingulskyi regional landscape park). The following carpological parameters of R. canina were investigated: 1) fruit’s length and width 2) nut’s length and width 3) mass of 1000 nuts 4) amount of nuts in a fruit 5) mass of 1000 fruits. The received data allowed to define criteria of variability and ecological flexibility of morphological features. As a result of our investigation, we found the following carpological feature of R. canina. In the environment of Northern Black Sea region R. canina shapes the fruits with the dimension of length from 0,8 to 3,0 cm (the mean is 1,5±0,01 cm) and with the dimension of width from 0,5 to 2,0 (the mean is 1,08±0,01 cm). The mass of fruits over a wide range varies from 0,2 to 3,2 g. The nuts’ dimension of length is from 0,3 to 0,5 cm (the mean is 0,4±0,01 cm) and the dimension of width is from 0,1 to 0,5 cm (the mean is 0,3±0,01 cm). The average amount of nuts in a fruit is 25 pieces. The mass of 1000 nuts is 18 g. The defined carpological feature of R. canina meets norms. The most constant carpological features of R. canina is the width of a fruit and the length of a nut with the 13-17% mean of variability. The length of a fruit, the amount of nuts in aggregate fruit and the width of a nut varies on the higher level (21-29%). The most variable feature is the mass of a fruit with a high level of variability (33%). The interesting results gives a comparison of variability of the aggregate fruit morphological features in different populations of a dog-rose in 3 investigated types of ecotopes. The highest parameters variability of the investigated features is observed in a dog-rose population in the Pryingulskyi regional landscape park. This can be explained by heterogeneous local terrain and the appropriate moisture conditions (ground water). Approximately high variability is observed in the Mykolaiv parks, which can be explained by more different conditions of city ecotopes and increased recreational activity. Approximately low variability of features was found in plants in the vicinity of Shevchenkove village, which can be explained by the homogeneity of conditions in plants growth. The high flexibility of morphological parameters is noted for the mass of a nut and the amount of nuts in a fruit (0,8-0,9), the average figures of a fruit length and width (0,6-0,7), the low for the length of a nut (0,2). This indicates the type of wide amplitude adjustment to growth conditions in the investigated ecotopes of different types.