In California, coccidioidomycosis is a disease acquired by inhaling spores of Coccidioides immitis, a fungus found in certain arid regions, including the San Joaquin Valley, California, USA, where 8 state prisons are located. During 2011, we reviewed coccidioidomycosis rates at 2 of the prisons that consistently report >80% of California's inmate cases and determined inmate risk factors for primary, severe (defined as pulmonary coccidioidomycosis requiring >10 hospital days), and disseminated coccidioidomycosis (defined by hospital discharge International Classification of Disease, Ninth Revision code). Inmates of African American ethnicity who were >40 years of age were at significantly higher risk for primary coccidioidomycosis than their white counterparts (odds ratio = 2.0, 95% CI 1.5-2.8). Diabetes was a risk factor for severe pulmonary coccidioidomycosis, and black race a risk factor for disseminated disease. These findings contributed to a court decision mandating exclusion of black inmates and inmates with diabetes from the 2 California prisons with the highest rates of coccidioidomycosis.