Chronic mucocutaneous candidiasis (CMC) is a rare syndrome characterized by persistent and refractory infections of the skin, nails and mucosal tissues by yeasts of the genus Candida. Defects in the cellular limb of the immune system are well documented in CMC patients, but non-specific immune defects, such as myeloperoxidase deficiency or phagocyte chemotaxis disorders, have also been described. Nonetheless, the underlying defect(s) remains poorly understood, and further studies are required. We studied eight CMC patients without endocrinopathies, who showed (i) low normal proliferative response to phytohaemagglutinin (PHA), (ii) partially defective response to pokeweed mitogen (PWM), and (iii) impaired response to Candida and PPD antigens. Furthermore, peripheral blood mononuclear cells (PBMC) from CMC patients produced lower levels of type-1 cytokines (IL-2 and interferon-gamma) in response to Candida antigens, compared with control individuals. Conversely, we did not observe an enhancement of IL-4 and IL-10 in the patients, suggesting that, even though Th1 cytokines are decreased, the Th2 response is not increased in CMC. Nevertheless, the synthesis of these cytokines was normal when induced by PHA. We also observed an increased antigen-induced apoptosis in lymphocytes from the patients compared with controls, and this applied both to Candida and PPD antigens. Lastly, innate immunity defects were investigated. We observed an impairment of natural killer activity against K-562 target cells in half of the studied patients. These findings corroborate the extensive clinical and laboratory variability of CMC, which requires further studies on a larger number of patients to be better understood.