Previous Ethnopharmacological studies have showed the use of Phenax rugosus (Poir.) Wedd. and Tabebuia chrysantha G. Nicholson leaves for the treatment of infectious diseases and in inflammatory processes. Aqueous and methanolic extracts of each plant was obtained in order to determine the capacity of these extracts to induce significant changes in the seric levels of IgM and IgG2b antibodies in Wistar rats. The results obtained show that these extracts do not produce a response with statistical significance when comparing the antibody levels between the control and treatments groups.