The costs of ventilation for underground uranium mines to meet the existing radiation-exposure standard were estimated for 14 mines, representing over half of the underground uranium production in the United States. All of the mines used the room-and-pillar system of mining, all were in sedimentary formations, and mine depth ranged from 300 to 2,700 ft. Using the information obtained from the mines, the costs were estimated for meeting more stringent exposure standards using dilution ventilation only, and other control methods in combination with dilution ventilation. A theoretical engineering analysis of the ventilation system requirements that would be needed in each mine to comply with the more stringent standards was performed. The harris and bales equation was used to estimate the increased airflow required to achieve the lower mine average working levels that were needed to meet the more stringent standards. Projected costs for meeting the more stringent standards were based on the increased capital and operating costs of the higher capacity ventilation systems. Two mines were analyzed to determine the cost- effectiveness of other control methods (i.e., sealants, bulkheads, and filtration), in combination with dilution ventilation.