The article examines the peculiarities of influence of operating environment an enterprise on business processes. Considerable attention is paid to negative influence of external environment, in particular, seven factors in the process of growth of inertia are highlighted, namely: 1) fierce competition; 2) limited resources; 3) complexity and high cost of logistics operations; 4) institutional restrictions; 5) destabilization of financial system; 6) change of standards and norms; 7) reduction of target markets. The factors of negative influence of internal environment are singled out as a set of manifestations of economic security destabilization in order of increasing inertia, which are 1) ineffectiveness of research work at an enterprise; 2) problems of responsibility areas distribution; 3) problems of managing operational processes; 4) low efficiency of marketing system; 5) insufficient financial support; 6) absence of effective control system; 7) conflicts; 8) workers’ opportunistic behaviour. The article assesses the deterioration of an enterprise business process, taking into account the listed factors of negative impact. Such assessment is carried out by experts, in particular, experts are asked to give corresponding percentage of decline in the assessment of the state of this process for each business process on a scale of 0, 25%, 50%, 75% or more. The testing was carried out at the "Khmelnitskhezelezobeton" enterprise with 34 experts being involved. The article provides a matrix of average percentages of decline during a month and a matrix of intensities of decline for the enterprise under study. The result of using the model is ensuring the economic security of the enterprise making effective management decisions for minimizing the negative impact of operating environment of the enterprise.