Polybia paulista, a very common wasp in São Paulo state, is responsible for many accidents of medical importance due to its venom. Thus, the characterization of the main venom allergens, through the determination of sequence, structure and organization of its genes and proteins, as well as, the action mechanisms of these components is very important. The cDNA was obtained from mRNA extracted from insect abdomens and amplification by RACE-PCR using gene-specific primers. A band of 300 bp was obtained, purified and sequenced. The resulting data were analyzed and compared with similar sequences from GenBank. The Ag5 fragment displayed high identity of nucleotides (98%) and of amino acids (92%) with Polybia scutellaris-Ag5 and lower identity with that from Polistes exclamans and Polistes annularis. Due to these high identity levels, this partial sequence should correspond to half of the complete P. paulista Ag5 cDNA sequence. The protein fragment presented 75 amino acids and molecular weight of 8,5 KDa. This also presented similar domains to the same protein Ag 5 in another wasp species, such as, Vespula vulgaris, Polistes annularis and Dolichovespula maculata and to a similar allergen found in Solenopsis invicta ant venom. Other similar proteins were the PR-1 and GliPr, that are related to pathogenic processes found in plants and humans respectively, and CRISP 2 and a glycoprotein, member of the secretory proteins family from rats and mices epididymis. This allergen complete cDNA sequence will allow the determination of other conserved regions and of those responsible for the immunological process. Besides, it will also allow obtaining information for the expression of the recombinant protein, purification, determination of the P. paulista Ag5 three-dimensional structure and the characterization of its immunogenic properties.