Abstract. The Triatoma infestans salivary gland proteins (TSGP) can induce local and systemic hypersensitivity reactions in humans. IgG antibodies against TSGP were present in higher levels in sera of Chagas disease patients, and in individuals living in triatomine-infested areas than in controls living in triatomine-free areas. TSGP-specific IgG 1 was found in sera of Chagas patients, and of individuals living in triatomine-infested rural areas, and uniquely specific IgG 4 was present in sera of Chagas patients living in triatomine-infested areas, reactive against TSGP. Unique specificities were not detected in sera of individuals reacting against the ubiquitous mosquito Culex quinquifasciatus saliva proteins (CSGP). In conclusion, IgG 1 reactive against TSGP is the main antibody present in individuals living in the triatomine-infested study areas. Also, IgG 4 is found in the sera of insect-transmitted Chagas disease patients living in study areas.