Introduction. The article examines the problem of adaptive response to cognitive activity in primary schoolchildren with different individual psychological characteristics. The objective of the research is to study the response of the autonomic nervous, cardiovascular and endocrine systems to cognitive load in primary school children with different levels of anxiety and neuroticism. Materials and Methods. The research sample consisted of 38 primary schoolchildren. The data for this study were collected using the following methods: spectral and temporal analysis of heart rate variability, electrocardiography, bipolar reoencephalography, tonometry and enzyme-linked immunosorbent determination of cortisol in saliva. The levels of anxiety were identified using the CMAS scale adapted by A.M. Prikhozhan. In order to assess the level of neuroticism, the authors applied the Eysenck Personality Questionnaire. The cognitive load involved working with digital Schulte tables. Results. The authors found that the type and intensity of the reaction of the autonomic nervous, cardiovascular and endocrine systems in primary schoolchildren depend on personal characteristics (the level of anxiety and neuroticism). The study revealed that children with medium anxiety and low neuroticism levels showed the most beneficial organism response to cognitive load. The most pronounced and generalized reaction of the organism was indicated among schoolchildren with high levels of anxiety and medium levels of neuroticism. It was revealed that the hyperactivity of the autonomic nervous, cardiovascular and endocrine systems in primary schoolchildren with high levels of anxiety and neuroticism was determined by the initially high level of the studied indicators. Conclusions. The response of the autonomic nervous, cardiovascular and endocrine systems to cognitive load is stressful for primary schoolchildren with increased and high levels of anxiety and neuroticism. In this regard, the authors emphasize the need for psychological and teaching interventions aimed at measuring and treating anxiety disorders in primary school children.