Recently many studies have described the effects of urbanization on species behavior and adaptation. The species Apodemus uralensis and A. sylvaticus were captured with live traps in urban ecosystems of Chișinău city. The study of the interspecific relations between the two species were carried out by the method of pair encounters. In interspecific relations of A. uralensis and A. sylvaticus various types of olfactory contacts were established: naso-nasal, naso-lateral, naso-dorsal, naso-ventral. In the interspecific contacts of the females, aggressive elements were registered, but in small numbers. A. sylvaticus females explored the environment (36.9% of the experiment duration) and actively tried to familiarize themselves with the partner – the number of contact initiations increased 2 times compared to intraspecific contacts and was 2.4 times higher than the analogous index of females A. uralensis. In A. uralensis females the complex of defensive behavior increased considerably: practically at each contact initiation, they responded through aggressive postures or shrill sounds. The duration of the freezing was 2 times longer than that of the exploratory activity, while the last one decreased by 1.3 times. Compared to intraspecific contacts, the noise level increased 3.7 times and the number of aggressive postures - 5.2 times. According to the obtained data, the reciprocal olfactory contacts (naso-nasal, naso- anal, naso-lateral) have a great importance for the social relations of rodents and depend on the social status, season and sex of the partners. When the specimens of different species are placed in pairs, the olfactory contacts last 10 - 40 sec. The number of olfactory contacts is maximum in the first 5 minutes of the experiment, during the establishment, the formation of mutual relations between animals. All the listed characteristics of representatives of A. sylvaticus allow us to conclude that this species has high adaptive abilities, great potential and resistance to overcome the negative conditions of “tension” community.