This research was supported by Brazilian grants from Fiocruz (PAPES V and PDTIS), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). We thank the staff of the Toxinology and Pathology Laboratories-IOC/Fiocruz for excellent technical assistance. We gratefully acknowledge Dr. André Teixeira S. Ferreira and Dr. Richard H. Valente (Toxinology Laboratory-IOC/Fiocruz) for their assistance with the mass spectrometric analysis. We also thank Monique R. O. Trugilho (Toxinology Laboratory-IOC/Fiocruz) for helping with 2-DE gel image analysis. We are grateful to Heloisa M. N. Diniz and Cristina S. Ferreira (Image Production and Treatment Service - IOC/Fiocruz) for processing the figures and creating the life cycle cartoon. KMR thanks CAPES for her PhD fellowship. PCC thanks CAPES/Fiocruz 30–2006 for his fellowship.Angiostrongylus costaricensis is a nematode helminth that causes an intestinal acute inflammatory process known as abdominal angiostrongyliasis, which is a poorly understood human disease occurring in Latin America. Our aim was to study the proteomic profiles of adult parasites focusing on immunogenic proteins. Total cellular extracts from both genders showed similar 2-DE profiles, with 60% of all protein spots focused between pH 5–7 and presenting molecular masses from 20.1 to 66 kDa. A total of 53 different dominant proteins were identified in our dataset and were mainly associated with the following over-represented Gene Ontology Biological Process terms: “macromolecule metabolic process”, “developmental process”, “response to stress”, and “biological regulation”. Female and male immunoblots showed similar patterns of reactive proteins. Immunoreactive spots identified by MALDI-PSD were found to represent heat shock proteins, a putative abnormal DAuer Formation family member, and galectins. To date, very few biochemical analyses have focused on the nematode Angiostrongylus costaricensis. As such, our results contribute to a better understanding of its biology and the mechanisms underlying the host–parasite relationship associated with this species. Moreover, our findings represent a first step in the search for candidate proteins for diagnostic assays and the treatment of this parasitic infection.