Urban Green as part of urban ecosystems can be divided into three different types: street trees, lawns/ parks and urban forests (BOLUND & HUNHAMMAR, 1999). These three types generally have different extensions as well as structures. The influence they exert on their surroundings depends on their size and composition (lawn, bushes, and trees). In cities, vegetation generates a variety of services, e.g. noise reduction, air filtration and micro climate regulation. The latter is due to modifications in incoming and outgoing radiation fluxes, including the fluxes of latent and sensible heat, air temperature, wind conditions and air humidity. These effects contribute to mitigating the urban heat island on a local scale. This paper is analysing the thermo_physiological impact of urban green and discussing its importance for human health at present and in a changing climate.