Assessment of reliability of mine ventilation systems of operating mines in Russia shows that its level is extremely low. Mine ventilation systems are characterized by frequent failures in the amount of air supplied to the places of consumption, which leads to the possibility of gas and dust explosions and poisoning of workers. Almost all accidents at mines resulting in the biggest losses of life are connected with failures of mine ventilation systems. For estimation of failures the integral criterion is offered, which characterizes the probability of failures, connected with reduction of air inflow into a mine due to increase of its resistance and redistribution of air in a network because of difference of actual values of its elements resistance from the design ones.
