Coccidioidomycosis is a systemic infection caused by the inhalation of airborne arthroconidia from Coccidioides immitis, a soil-dwelling fungus found in the southwestern United States, parts of Mexico, and Central and South America. Clinical manifestations occur in approximately 40% of infected persons and may include mild influenza-like illness; severe pneumonia; and rarely, disseminated disease and death. During 1990-1995, the number of reported cases of coccidioidomycosis in Arizona increased by 144%. To characterize trends in and the impact of coccidioidomycosis in Arizona, the Arizona Department of Health Services (ADHS) analyzed surveillance, death-certificate, and hospital discharge data. This report summarizes the findings, which indicate that, during 1990-1995, coccidioidomycosis in Arizona disproportionately affected persons aged > or = 65 years and persons with human immunodeficiency virus (HIV) infection.