Subject of the paper is to present results of two comparative studies carried out in the historical part of Kaunas city (Lithuania). The first one was related to the regeneration project of this area elaborated in 1969 while the second one was repeated twenty years later following the completion of this project implementation. The first one of those studies disclosed the phenomena of very intensive concentration of numerous asocial, deviated behavior in the local community. Interaction between various levels of environment and intensity of these phenomena were mathematically verified: the coefficient of correlation calculation has shown the existence of close interrelationship between them. It enabled to select the most acute drawbacks and evils of environment and to formulate the programme of their gradual elimination. The programme of this project implementation was based on the sociology survey of local inhabitants, respectively to the reiteration of the mentioned undesirable features of living environment. Thanks to the two decades consequent implementation of this programme that initiated numerous essential urban, functional and architectural changes in the old part of Kaunas city: previously deteriorated historical kernel had become the representative and attractive part of the city. Twenty years later as the implementation of the regeneration project has been completed, the research of this area was repeated keeping to the same scale, methodologies and procedure as the pre_project before. Its results revealed evident positive changes in both physical and psychological health of local population, its life style and well being. This fact has been proved again by the new mathematical interpretation of summarized data.