The authors prove the relevance of the study of the effectiveness of professional activities of employees in relation to personal characteristics and functional states in extreme conditions, especially in conditions of the shift work in the Far North. The purpose of the study was to analyze the interrelationship between the efficiency of professional activities of shift workers in a mining and processing factory with their social and psychological qualities and functional states during the shift-work period. Study group: 41 shift workers of the mining and processing factory of one of the diamondiferous deposits of the Arkhangelsk region. Methods of research included the psychological testing, set of psychophysiological techniques. The research show the social-psychological characteristics of the personality such as an evaluation of others as an etalon of oneself, moderate severity of altruistic type of attitude towards people, desire to achieve results in their activities at an average level, ability to control one’s feelings and emotions to be important for the effectiveness of the professional activity of shift specialists. The states of high effective workers are estimated at the level of the norm according to the indices of well-being and mood, the activity is estimated below the norm. The states of high-performance workers are also characterized by heteronomy and a strong degree of predominance of the right hemisphere. Average effective workers have a setting for the result at a level above the average, developed the ability to control one’s feelings, responsibility towards people. The states arising in the course of the labor activity, average-effective workers are estimated to be on average higher than the group of highly efficient workers. They are more autonomous and have a small degree of predominance of the right hemisphere. Employees, judged by experts as average-effective, resort to the use of the adaptation strategy for the emergency job, highly effective workers use economical strategy.