Abstract: Forests are complex ecosystems rich in diverse organisms, and an important part of the zoocenosis of lowland continental forests in Croatia are small rodents that periodically, in years of mass occurrence, significantly hinder natural regeneration; especially in oak and ash stands, and they are known natural reservoirs of numerous zoonoses. Within the proposed study, the structure and composition of populations of small rodents were determined in autumn 2021 in a total of six ash stands located in three forest offices (Stara Gradiška, Nova Kapela, Strizivojna) within the territory of two Forest Administration branches (Nova Gradiška and Vinkovci). The purpose of the research was to contribute to a better understanding of the activities, harmfulness, and prospective needs for implementing protective measures against the adverse effects of small rodents in the studied area. The method of linear transect with the use of 50 traps in each selected stand (total of 300) during one hunting night was applied to determine the relative abundance of rodents, and the captured individuals of rodents were visually identified to the level of species or representative of subfamilies. Through the undertaken monitoring, three species from the subfamily Murinae (mice) were identified (striped field mouse (Apodemus agrarius, Pall.), yellow-necked field mouse (Apodemus flavicollis, Melch.), wood mouse (Apodemus sylvaticus, L.)) as well as one species from the subfamily Arvicolinae (voles) (bank vole (Clethrionomys (Myodes) glareolus, Schreb.)). The subfamily Murinae was represented with a total of 90% of individuals compared to 10% of individuals from the subfamily Arvicolinae in the entire research area. The total determined relative abundance of rodents was 16%, varying in the range from 2% to 34% at the monitored sites. The determined relative abundance suggesting the implementation of protective measures was found in the Forest Administration branch Nova Gradiška, in the forest office Stara Gradiška. The conducted research emphasizes the importance of systematic monitoring of rodents, especially in stands with compromised vitality such as stands of common ash, in order to timely implement adequate protective measures to prevent significant damage from small rodents.