The purpose of this report is to describe the principles and applications of methods by which radiation hazards may be controlled in mines. Although primarily directed to the uranium mining industry, the information presented in this report may be applied in varying degree to all mines. Miners are exposed to airborne radon, thoron, and their short-lived decay products, to ore dust and, in some mines (particularly uranium and thorium mines) to external gamma and beta radiations. In general, the short-lived radon decay products present the dominant radiation risk. Radon is a member of the decay chain of uranium which makes up about 3 ppm of the earth’s crust. Consequently, radon is not limited to mines; it occurs everywhere, outdoors in usually low concentrations and indoors in higher concentrations. In underground mines, the concentration of these radioactive contaminants, in the absence of adequate control measures, can reach relatively high values. The scope of this report excludes the treatment of the other hazards, mechanical and toxic, that are characteristic of all mining operations. However, the protective measures developed to control radiation exposures may influence the situation regarding other hazards.