In an attempt to understand better the immunoregulatory disorders in paracoccidioidomycosis (PCM), the possible correlation between interleukin pattern, lymphoproliferation, C-reactive protein (CRP) and specific antibody levels was investigated in the polarized clinical forms of this disease. We studied 16 PCM patients, eight with the disseminated disease (four under treatment and four non-treated) and eight with the chronic disease. The patients with disseminated disease exhibited high antibody titres specific to Paracoccidioides brasiliensis antigen compared with patients with the chronic form of disease. Tumour necrosis factor (TNF), IL-1, IL-6 and CRP in the serum of non-treated disseminated PCM patients were increased, which correlated positively with the low mitogenic response of peripheral blood mononuclear cells (PBMC) to phytohaemagglutinin (PHA) (P < 0.01) and with the high antibody titres (P < 0.001) of these patients. Moreover, we found in the disseminated PCM patients positive correlations between IL-1 and IL-6 (P = 0.0007); IL-1 and TNF (P = 0.0045); IL-1 and IL-6 with the high antibody titres (P = 0.0834 and P = 0.0631, respectively); IL-1, IL-6 and TNF with CRP levels. By contrast, no correlations were found with those interleukins in the treated disseminated and chronic patients or in controls. It was interesting to find an inverse correlation between IL-4 and antibody production in non-treated disseminated PCM (r = -0.4770); moreover, a significant correlation (P = 0.0820) was found in chronic PCM patients with respect to the low level of either IL-4 and antibody titres against fungus antigen. Chronic PCM patients also had IL-2 levels inversely correlated with antibody production (r = -0.6313; P = 0.0628). Inverse correlations were also observed between IL-2 and IL-6 levels in non-treated disseminated patients (P = 0.0501) and between IL-2 and IL-4 in chronic patients (P = 0.0131). The inflammatory cytokines might have a pivotal role in the genesis and in control of some aspects of the disease, such as granulomatous reaction, hypergammaglobulinaemia and depression of T cell-mediated immunity in PCM.