Experimental local mammary gland Candida krusei infection in immuno-competent and in congenic athymic nude BALB/c mice over a period of 21 days demonstrated that the immunocompetent mice readily cleared the infection whereas the infection persisted in the athymic mice. The fungal burden, however, was similar in the nude mice and in the immuno-competent mice until day 18 after infection. The ratio of interferon-γ/interleukin-4 (IFN-γ/IL-4) concentrations in supernatants from ConA stimulated splenocytes of the infected mice indicated a predominant Th1 response to the C. krusei infection. Stimulated splenocytes of the infected immuno-competent mice synthesised significantly higher concentrations of the two cytokines than did the splenocytes from the infected nude mice. The present study indicates that local C. krusei infection is associated with a predominant IFN-γ-Th1 response although a gradual activation of the Th2 -arm (IL-4) of the immune system may be indicated late in the course of infection.