AIMS: To evaluate the effectiveness of photodynamic therapy with Brilliant Blue G in the treatment of an experimental model of arthritis by Paracoccidioides brasiliensis (P. brasiliensis). METHODS: After the induction of experimental arthritis with isolated from P. brasiliensis of lineage Pb18 in the knees of Wistar rats, the animals were divided into groups and submitted to photodynamic therapy with intra-articular Brilliant Blue G photosensitizer and laser therapy only, without Brilliant Blue G. All groups received their respective treatments from the seventh to the 11th day. For edema analysis, the knee lateral-lateral diameter of each animal was measured daily and after the treatment period the animals were sacrificed for experimental knee dissection and blood collection for analysis by ELISA, in order to quantify levels of anti-P. brasiliensis antibodies. RESULTS: The results showed that the application of photodynamic therapy was able to prevent the formation of edema when compared to the control (p>0.005), as well as the production of anti-Gp-43 antibodies from P. brasiliensis (p=0.001). In the anatomopathological examination it was possible to observe a higher degree of synovitis and a greater presence of granulomas with the fungus inside the group that did not receive treatment when compared to the groups that received the photodynamic therapy. CONCLUSIONS: Photodynamic therapy was effective in attenuating the experimental arthritis induced by P. brasiliensis in the proposed joint model.