Abstract <p>Radiation therapy using carbon ions has a high therapeutic potential and a number of advantages compared to other ion types. It is successfully used to treat certain types of cancer, such as brain tumors. However, there are currently few studies on the effects of this type of radiation on the behavior and cognitive abilities of mammals, both in the short and long term after exposure. To date, there are both experimental and epidemiological data available on the cognitive effects of low and moderate doses of ionizing radiation (Britten et al., 2021; Kovalchuk and Kolb, 2017; Pasqual et al., 2021). These studies suggest that the underlying mechanisms involve disruptions in normal neurogenesis in the hippocampus, prolonged neuroinflammation, changes in synaptic plasticity, and alterations in energy metabolism and oxidative balance in the brain. It is important to study the effects of carbon ions on delayed radiation therapy-related brain irradiation complications, such as depression, anxiety, memory impairment, and learning difficulties. In this study, we investigated the effect of the local irradiation of mouse heads with accelerated carbon ions (450 MeV/n) at doses of 0.7 and 2 Gy on behavior and cognitive function. We found that two months after irradiation, mice did not exhibit a changed behavior pattern and there was no impairment of long-term memory dependent on the hippocampus. However, we did detect a deterioration of episodic memory. The obtained results are important to consider when assessing the risk of cognitive impairment in astronauts and patients undergoing hadron therapy.</p>