Because of the increase in incidence of coccidioidomycosis among the elderly in Arizona between 1990 and 1996, a case-control study was conducted to look at risk factors for disease among these persons. Cases (n=89) were persons aged > or =60 years with laboratory-confirmed coccidioidomycosis; 2 control groups were selected, the first by use of random-digit dialing (geographic controls, n=91) and the second by use of lists of persons with negative serologic coccidioidomycosis tests (laboratory-negative controls, n=58). Elderly persons with coccidioidomycosis had spent significantly less time in Arizona than did persons in either control group and were more likely than geographic controls to have congestive heart failure or cancer, to have smoked, or to have taken corticosteroids. Elderly persons who recently have moved to Arizona or who have chronic illnesses and their physicians need to be aware of their higher risk for coccidioidomycosis in order to improve their chances of early diagnosis and treatment. These persons may benefit from vaccination, once an effective vaccine for coccidioidomycosis is developed.