A continuous survey of radon gas was made in two interconnecting stopes in a southwestern U.S. uranium mine to determine how the various phases of the mining cycle affected the radon concentration. The radon was monitored continuously with five detectors. One detector monitored the intake air, one the exhaust air, and three the stope air. The radon concentrations present during slushing, blasting, and exhaust fan shutoff were compared with concentrations on a nonwork day as a base level. Inside the stope, the radon concentration increased about 40 percent during slushing and 425 percent after blasting. Intake air radon increased 1,600 percent and the stope air increased 550 percent while the surface exhaust fan was off.