The aim of our work was to analyse synanthropic fraction of spontaneous flora of gardens and parks in the Middle Pobuzhzhia Region of Ukraine and to reveal the features of synanthropisation. The landscapes of gardens and parks in the Region include botanical gardens, arboretums and monuments of landscape art. A total of 15 objects were studied. The floras of parks were estimated by proportion of different groups (origin, naturalisation degree, time and ways of introduction) of synanthropic species. The synanthropic fraction of spontaneous flora was calculated using the indices of synanthropisation, apophytisation, anthropophytisation, archeophytisation, kenophytisation and modernisation. These indices were specified for each park and for the Middle Pobuzhzhia Region in general. The obtained data were compared to each other and to the analogous urban floras from different zones of Ukraine. It was revealed that the apophytisation processes were dominated by the processes of adventisation in most of the parks. The proportion of the synanthropic fraction of spontaneous flora of the Middle Pobuzhzhia Region was significantly lower compared to urban floras of some cities of Ukraine, and despite a considerable anthropogenic pressure retained some features of natural flora.