Mice receiving patulin (10 mg/kg) from 1 to 4 days showed enhancing resistance to intraperitoneal challenge with 10(8) viable Candida albicans at day 2. Resistance to C. albicans infection (10(6) blastospores) appeared to be unchanged after cyclophosphamide oral administration (60 mg/kg). Immunoglobulins levels (IgA, IgM, IgG) are marked depressed (10 to 75%) in mice infected and/or treated by patulin and cyclophosphamide. The results show that an increase of neutrophil count may be among the factor underlying the late increase in resistance to C. albicans after administration of patulin.