Mycobacterium tuberculosis (H37Rv)-infected guinea-pig model was used to investigate the effect of water extract of propolis (WEP). After subcutaneous inoculation of tubercle bacilli, each animal received oral WEP (n = 9), isoniazid (n = 5) or saline (n = 6) as placebo and were sacrificed 30 days later. Formation of necrosis was less prominent in the group treated with WEP, but was not statistically significant (P > 0.05). The granuloma formation in the same group was more prominent than the placebo and isoniazid groups; however, this finding failed to reach statistical significance by the Kruskal-Wallis test (P > 0.05). These findings suggest that Turkish WEP may have a limited effect on the development of tuberculosis infection in this guinea-pig model. (C) 2003 Elsevier Ltd. All rights reserved.