Paracoccidioides brasiliensis, a dimorphic fungus, is the etiologic agent of Paracoccidioidomycosis (PCM), one of the most important systemic mycosis in Latin America. Two genes (2.2 and 1DB5) were cloned, characterized and sequenced; they showed homology with members of hsp70 gene family. By using several probe fragments derived from these genes, levels of expression for each gene were determined by Northern blot during transition to the yeast phase. The highest level of hsp70 transcript occurred between 30 min to 6 hours after temperature shift, with significant reduction after 36-48 hours. However, after 72 hours, the level of the transcription increased until yeast phase was reached. As a response to temperature increase, hsp 70 genes are expressed during the transition phase and possibly play a role in the differentiation process.