Objective: To evaluate the ability of Actinomadura madurae(A. madurae) and Nocardia asteroids(N. asteroides), using Candida albicans(C. albicans) as prototypic control, to elicit the activation and IL-1β secretion of blood phagocytic cells from healthy donors. Methods: Microcopic evaluation of phagocytosis/activation, cell viability and spectrophotometric quantitation of endocytosis/activation, were assessed by using formazan blue test in human blood phagocytes infected with C. albicans, A. madurae or N. asteroides treated with either normal human serum(NHS) or with decomplemented NHS. Interlukin-1β from culture supernatants of infected polymorphonuclear was tested by ELISA kit assay. Results: Microscopic assay showed that phagocytosis and activation of adherent mononuclear phagocytes were greater with C. albicans followed by A. madurae and then by N. asteroides. Spectrophotometric assay in polymornuclear phagocytes infected with NHS-treated pathogens indicated that activation was similarly higher by C. albicans and A. madurae and lower by N. asteroides. Kinetic assays in infected polymorphonuclear cells showed that viability was decreased by C. albicans and N. asteroides or unaffected with A. madurae. Levels of IL-1β at 8 h of incubation were higher with C. albicans followed by A. madurae whereas lower levels were found with N. asteroides. Conclusions: The extent of cell-viability and activation as well IL-1β secretion may be related with the virulence of C. albicans and N. asteroides and other parameters remain to be explored for assesing the virulence of A. madurae. Objective: To evaluate the ability of Actinomadura madurae (A. madurae) and Nocardia asteroids (N. asteroides), using Candida albicans (C. albicans) as prototypic control, to elicit the activation and IL-1β secretion of blood phagocytic cells from healthy donors. Methods: Microcopic evaluation of phagocytosis / activation, cell viability and spectrophotometric quantitation of endocytosis / activation, were assessed by using formazan blue test in human blood phagocytes infected with C. albicans, A. madurae or N. asteroides treated with either normal normal human serum (NHS) or with decomplemented NHS. Interlukin-1β from culture supernatants of infected polymorphonuclear was tested by ELISA kit assay. Results: Microscopic assay showed that phagocytosis and activation of adherent mononuclear phagocytes were greater with C. albicans followed by A. madurae and then by N. asteroides. Spectrophotometric assay in polymornuclear phagocytes infected with NHS-treated pathogens indicated that activation was si milarly higher by C. albicans and A. madurae and lower by N. asteroides. Kinetic assays in infected polymorphonuclear cells showed that viability was decreased by C. albicans and N. asteroides or unaffected with A. madurae. Levels of IL-1β at 8 h of incubation were higher with C. albicans followed by A. madurae than lower levels were found with N. asteroides. Conclusions: The extent of cell-viability and activation as well IL-1 beta secretion may be related with the virulence of C. albicans and N. asteroides and other parameters remain to be explored for assesing the virulence of A. madurae.