Naturally occurring sulfates are common contaminants of groundwater. Dissolved sulfates are used by sulfate reducing bacteria which release hydrogen sulfide. Sulfate reducing bacteria are common in anaerobic environments such as deep wells. This results in production of hydrogen sulfide, a corrosive gas. Monitoring and control of sulfate reducing bacteria may be used to control the formation of hydrogen sulfide. To this end, the present study examined the prevalence of sulfate-reducing bacteria from five groundwater sources on the Mogollon Rim in central Arizona. The five samples were negative by both assays. Results serve as a basis for future study of ground-water microbiology and sulfate-reducing geochemistry in the Mogollon Rim.