In spite of a far-reaching research effort extending over many years the processes by which the human body acquires immunologic resistance to most of the chronic infectious diseases remain obscure. With few exceptions, methods by which such resistance may be artificially produced or stimulated have not been discovered. In coccidioidomycosis there are several instances in which the immunologic reactions seem to be less complicated than those encountered in tuberculosis, for example. More concentrated research in coccidioidomycosis might lead to a better understanding of immunologic processes in general.