Specific and total IgG and IgE serum levels were measured in Sprague-Dawley rats after immunization with ovalbumin (OA). OA was administered in an aqueous solution, suspended in alum or in Complete Freund's Adjuvant (CFA) with or without simultaneous administration of Bordetella pertussis (Bp). Control groups received only saline, alum or CFA. Specific IgG, total IgG and total IgE were determined by ELISA methods. Specific IgE was biologically evaluated. The highest specific IgG and IgE antibody responses were obtained with OA suspended in alum, while Bp failed to potentiate this response. The low specific response seen with OA suspended in CFA was potentiated when Bp was simultaneously dosed. Total IgE levels were increased in those groups receiving Bp. The contribution of specific IgG or IgE response to the total IgG or IgE levels was not distinguished with this experimental procedure. It can be concluded that immunization with OA suspended in alum induces appreciable increases in specific IgG and IgE antibodies without significantly affecting total IgG and IgE levels.