1. The course of experimental paracoccidioidomycosis was studied in alcohol-fed rats and compared with pair-fed and ad libitum controls. The alcohol-fed rats were fed a regular commercial solid diet plus a 32% (v/v) ethyl alcohol-25% sucrose (w/v) solution 4 weeks prior to the infection and throughout the study. The inoculum was standardized in terms of virulence, age of culture, percentage of multicellular fungal units containing 1-3 cells and viability. 2. The extent of infection was measured by quantitative counts of fungal units (FU), colony-forming units (CFU) of Paracoccidioides brasiliensis from infected pulmonary tissue and histopathological examination of the main organs involved. The specific humoral response and cell-mediated immunity of the animals were assessed by measuring the specific serum antibody levels by counterimmunoelectrophoresis (CIE) and by the footpad swelling test (FST), respectively. 3. Alcohol-fed rats and pair-fed controls did not differ significantly in mean body weight or the extent of disease after 5 and 10 weeks of infection. In contrast, the alcohol-fed group when compared with the ad libitum group presented a significantly lower mean body weight (301.6 +/- 0.6 vs 389.6 +/- 0.7 g) and a larger number of fungi recovered from the lung: 81.1 +/- 4.1 x 10(4) vs 13.4 +/- 8.0 x 10(4) FU; 24.3 +/- 8.6 x 10(4) vs 2.9 +/- 0.5 x 10(4) CFU after 5 weeks of infection. There were no significant differences in the specific antibody levels, FST indices, histopathological pattern of frequency of disseminated lesions between groups.(ABSTRACT TRUNCATED AT 250 WORDS)