Coccidioidomycosis is an infection caused by the fungus Coccidioides immitis, which resides in the soil in some areas of Arizona, California, Nevada, New Mexico, Texas, and Utah. Infection can occur when airborne, infective arthroconidia are inhaled. Symptomatic coccidioidomycosis, which occurs in approximately 40% of all infections, has a wide clinical spectrum, including mild influenza-like illness, severe pneumonia, and disseminated disease. Beginning in 1991, the number of cases of coccidioidomycosis reported annually to the California Department of Health Services (CDHS) increased dramatically (1) (Figure 1). This report summarizes the occurrence of coccidioidomycosis in California during 1991-1993.