In southern Brazil, CRF31_BC is the major HIV-1 recombinant form and URFs_BC occurs very infrequently. The near full-length genomes of four samples displaying a similar recombination profile in the integrase region and different profiles in the protease=reverse transcriptase regions were analyzed to elucidate their mosaic structure and to describe for the first time the near full-length genomes of URFs_BC circulating in Brazil. For this purpose, overlapping PCR amplifications followed by direct sequencing were carried out. Despite the observation that these samples share a similar recombination profile in the integrase region, phylogenetic, bootscan, and informative site analyses revealed that the four samples displayed distinct mosaic structures. Additional recombination events occurred mainly in the gag, reverse transcriptase, and env regions. Our data provide the first description of the near full-length genomes of URFs_BC in Brazil and offer important insights about the complexity of HIV-1 recombinant strains currently in circulation in the south of Brazil..