We investigated the efficacy of fluconazole on experimental disseminated candidiasis in mice immunocompromised by chronic morphine treatment. CD1 mice were severely immunosuppressed by repeated morphine administrations, i.e., subcutaneous (s.c.) injections of 75 mg/kg/day, 3 days before and 5 days after a systemic Candida albicans infection induced by intravenous administration of 1 x 10(6) fungal cells/mouse. Fluconazole (2.5 mg/kg, s.c., at 6, 24 and 48 h postinfection) was very effective in prolonging survival time of morphine-treated mice. Fluconazole treatment also promotes a recovery of killing activity of polymorphonuclear leukocyte cells suppressed by morphine administrations.