Coloration of the green frogs (Rana ridibunda, R. lessonae, R. esculenta) is a phenotypic feature as the result of a long evolutionary process (Arnold et al., 1986). The major importance of coloration for amphibians consists in the role of thermoregulation, blinding enemies and not least the attraction of sexual partners (Dediu, 2007; Cozari, 2010; Gherasim, 2014). In order to study the polymorphism of the green frogs the original methodology has been applied, which comprises carrying out the series of successive images of the specimens in a short period of time on the whole surface of the habitat. Photos of all individuals in every aquatic habitat during active periods of life cycle and subsequent analysis for each species and specimen in part allowed us to get an overview of chromatic forms in the examined population. In evaluating data on the color of the green frogs was established that, with reference to the background color (ranging from gray to olive green), stains, lines and points of other colors, can be distinguished 12 types of morphs of dorsal coloration. Coloration is the result of interaction of genome with external factors; it has an adaptive character to focus on ensuring efficient vital needs for the species, which differs in different living conditions, but also in various phases of the annual cycle of green frogs. Thus, in late March, when the air temperature record values of +10°C and the water temperature was between +5° + 7°C (during spring) and green frogs specimens are coming out of hibernation, field and the lab work were established background color ranges from gray to grayish olive green with dark metallic sheen. In such environmental conditions among the populations examined were identified three basic morphs: Maculata (M), Striata (S) and Bursni (B). As a result, these phenotypes are formed as a combination of the maculata – striata (MS), maculata – hemistriata (MhS), hemimaculata (hM), hemistriata (hS) and bursni (B). Types of morphs identified for green frogs are not only an example of interaction between amphibians and environmental factors, in addition they also embody areas where they live in conformity both with the vegetation cover on land and dried aquatic flora from aquatic environment. While atmospheric values continue to rise, the air temperature reaching 30 + 350C and water 24 + 260C (summer) we have recorded a change in background color, in most cases it was light green. This background color variation is due not only to temperature change, but also because of bright substrate; where the dark color switch to the green. In the summer most frequent were the following four basic morphs: Maculata (M), Striata (S), Bursni (B) and Punctata (P). As with the basic morphs of the spring, these phenotypes form other combinations, such as: maculata striata (MS), maculata hemistriata (MhS), hemimaculata (hM), hemimaculata hemistriata (hMhS), striata hemipunctata (ShP), punctata (P) and hemipunctata (hP). Unlike the specific combined morph distribution that were registered during the spring-summer, towards fall as the temperature of air and water decreases, humidity changes, disappear optimum conditions for living. Among green frogs have been recorded a greater number of combined morphs: maculata (M), maculata striata (MS), maculata hemistriata (MhS), hemimaculata hemistriata (hMhS), punctata (P), punctata hemistriata (PhS), hemipunctata (hP), bursni (B), bursni striata (BS), striata (S) and hemistriata (hS). This demonstrates that in less favorable conditions of life amphibians are stronger dispersed throughout terrestrial and aquatic habitats and number of morphs obviously increases. The background dorsal color of green frogs is darker during spring and autumn, in addition to camouflage function, in particular this provides thermoregulation. Thanks to dark color, thermoregulation is provided by better level of absorption of solar energy that provides the appropriate functioning of physiological processes of specimens. In summer, when living conditions are favorable, the role of coloration is focused specifically on camouflage. Unlike chromatic forms of adult frogs, the young specimens are characterized by the dark color of background. Specificity of the dark color is explained by the vital needs for absorbing solar energy from the period of embryonic development, larval and juvenile stage. Since the embryonic and larval development of frog are only conducted in the aquatic environment and their specimens are prone to a higher risk of bearing the consequences of less favorable external factors and aquatic predators, dark chromatic provides the main functions of thermoregulation and protection. After analysis of determined morphs, we can conclude that the phenological changes is a continuous processes with adaptive capacity and operational response to environmental factors; morphs concerned homochromia show adaptations to the substrate, and this can protect from predators (waterfowl, some mammals and others) and ensure their thermoregulation. The work was performed within the project 15.817.02.12F financed by Academy of Sciences of Moldova.