The biochemical study of activity of serum cholinesterase in workers of industrial enterprise was carried out on the example of petrochemical industry. The indicators of average activity of enzyme and prevalence of indicators going beyond limits of reference values were analyzed depending on manufacturing-labor experience, profession and diseases established in workers. The main diseases, professional and labor experience groups were identified where activity of cholinesterase significantly changes. The impact of labor experience and profession on level of activity ofenzyme in blood serum is demonstrated.