<p>The inert gas argon has recently attracted attention from researchers due to its pronounced neuroprotective properties. These properties are mediated by argon’s ability to suppress inflammatory processes and apoptosis. However, the therapeutic potential of argon application during the neonatal developmental period remains poorly studied. The early neonatal period is characterized by heightened sensitivity of the central nervous system to damaging factors, particularly neonatal hypoxia. This study evaluated the ability of repeated argon inhalations to interact with the effects of neonatal hypoxia at the behavioral level and exert delayed effects on caspase-3 expression. Inhalations were administered using an argon-enriched gas mixture (74% Ar, 21% O₂, 5% N₂) or artificial air from postnatal days (PND) 3 to 10 in a model of single normobaric hypoxia (8% O₂ for 2 hours on PND 2). The results showed that argon inhalations marginally increased the number of orienting head turns in rat pups on PND 5 but significantly reduced the speed of righting reflex execution in the negative geotaxis test on PND 11. Repeated argon inhalations led to decreased exploratory activity in the Open Field test (PND 27) and impaired skill acquisition in the Complex Food Maze. Perinatal hypoxia, in turn, reduced the quality of vestibulospinal reflex execution and locomotion in the early postnatal period. In the late postnatal period, hypoxia suppressed exploratory activity in the Elevated Plus Maze and worsened learning ability in the Complex Food Maze. Thus, argon application during this developmental phase may exert undesirable effects on the emotional status of the animals. No differences in hippocampal caspase-3 expression levels on PND 55 were observed between the groups.</p>