Tree of heaven [Ailanthus altissima (Mill.) Swingle] (family Simaroubaceae) is known as an invasive woody species in urban, rural, and natural ecosystems in many parts of the world. In Slovakia, it is accepted as an invasive species included in the list of invasive alien species of the EU concern (Regulation No. 2019/1262). In this study, the spread of the invasive neophyte A. altissima populations was monitored in the immediate vicinity (1 km) of the Slovak University of Agriculture in Nitra in southwestern Slovakia in 2022. We recorded habitat type, GPS coordinates in the centre of the local populations, area of population (m2), average tree height (m), and management measures. The species colonized an area of 1,997 m2. The plant spread mainly in the habitat of extensively cultivated fields such as front gardens of buildings (31%) and in abandoned and unused areas (the species occupied 28% of the total area). We recorded a lower occurrence in the botanical garden (18%), next to the anti-flood dam (16%), along roads (4%) and in the orchard (3%). Approximately 15% (28 shoots) of the total number of 183 shoots were female plants that formed a high number of seeds. There was a high correlation between the area occupied by A. altissima with its above-ground organs and the average plant height (m) (r = 0.88).