There can be a complexity of health problems associated with multiple mold exposure. This chapter describes the most recent neuroimmune mechanisms of diseases caused by molds and mycotoxins in humans. The exact biological and chemical actions through which these mechanisms unfold are not completely understood. However, molds do produce metabolites such as mycotoxins and shed antigenic materials—namely, spores, hyphae, extracellular polysaccharides, and enzymes—that are toxic and/or cause immunologic responses. The chapter discusses detailed health and environmental history, environmental monitoring data, physical examinations, routine clinical chemistries, measurements of lymphocyte phenotypic markers, antibodies to molds, mycotoxins, neuronal antigen antibodies, leukocyte apoptosis, nerve conduction studies (NCS), brainstem auditory evoked potentials (BAER), visual evoked responses (VER), and other neurological testing. The illness of these individuals is referred to as a “mold mycotoxicosis,” and it involves the immune system, the lungs, the central and peripheral nervous systems, and generalized inflammatory and irritant responses to exposure to spores, hyphal fragments, mycotoxins, solvents, and other byproducts.