Three deep mines have been excavating the copper ore deposit in south-west Poland for about fifty years. Rock mass tremors and their effects such as rock bursts pose the most dangerous hazard which increases with intensity and depth of exploitation. The permanent growth of seismicity of the deposit necessitated the implementation of preventive activities into mining technology. Temporary and long-term as well as active and passive methods were developed to reduce or eliminate the hazard among which group winning blasting seems to be one of the most successful preventive technique. The paper aimed to assess seismic activity and the effectiveness of active prevention as well as to verify the connection between induced seismicity of rock mass and elements of blasting works. To realize the goal, seismic activity, the number of blasted faces, the number of explosives, and blasting-induced seismicity were analyzed. Moreover, the linear correlation coefficients between the aforementioned parameters and characteristics were calculated. One mining division of the Polkowice-Sieroszowice copper ore mine was investigated over three years during a high rate of seismic hazard and intense exploitation.