In this study, Swiss mice were experimentally infected with Paracoccidoides brasiliensis (Pb18) and we investigated the levels of gp43 in urine and plasma, anti-gp43 and IgG-gp43 immune complexes in plasma. These levels were correlated with the histopathological findings. Blood and urine samples were collected from mice at 7, 28, 56 and 84 days after intravenous inoculation of 10(5) yeast cells, and analysed by ELISA. The results showed increased levels of soluble gp43 in the plasma in all periods, and anti-gp43 IgG and immune complexes after day 28. High gp43 levels were detected in the urine, except for day 28, coincident with the presence of compact granulomas in lungs. All the infected mice showed fungal cells in the lungs, with initial granulomatous lesions at day 7, dissemination of lesions to other organs at day 56, and granulomas lacking the surrounding mononuclear cells infiltration, especially at days 56 and 84. Our results suggest that gp43 diffuses passively into the urine, and the determination of gp43 levels in urine samples may be a non-invasive alternative method for diagnosis and follow up of PCM. Further studies are needed to determine if the cellular immune response correlate with decreased urine gp43 levels.