Introduction. Work in oil and gas exploration is intense, carried out on a shift (fly-in-fly-out) basis in the open air with alternating day and night shifts. 
 The analysis of the studies revealed the lack of information regarding the trend in the functional states of workers with different shift modes.
 Materials and methods. The study involved fifty eight shift workers at an oil exploration enterprise in the southeast of the Russian Federation with a 30 days shift period. 
 The study aim was to identify and describe the features of the trend in functional states in shift personnel at an oil exploration enterprise in the southeast of the Russian Federation with various work and rest regimes. To solve the tasks set, daily the functional states’ monitoring in morning and evening by workers was carried out using objective hardware (VCM, CVMR) and subjective (WAM, M. Luscher test) methods. Statistical methods are multivariate analysis of variance and descriptive statistics.
 Results. The features of trend in objective and subjective parameters of the functional states in the shift personnel at an oil exploration enterprise in the southeast of the Russian Federation with various work and rest regimes are revealed: 30D, 15D / 15N and 15N / 15D. It has been established that the personnel at an oil exploration enterprise with a work regime of 15D/15N is characterized by a greater severity of unfavourable functional states by the end of the shift period. 
 Limitations. The study limitations are the small sample size, which is due to the study being carried out at one site with the inclusion of the maximum number of workers located at the facility during the expedition. Workers with work regimes 15D/15N and 15N/15D differed in functional duties from the group of employees with work regime 30D. 
 Conclusion. The results and conclusions obtained make it possible to expand knowledge about the changes in the workers’ states at oil and gas producing enterprises with different shift regimes during the shift period and develop practical recommendations for their optimization.
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