When a diagnosis of invasive candidiasis has been made, treatment with toxic fungicidal agents is inevitable. The crucial decision of when to stop such treatment is difficult to make, because cultures are often negative despite ongoing invasive candidiasis and can therefore not be used as a reliable parameter of effective therapy. In the present study, the use of PCR in monitoring the therapeutic efficacy of antifungal treatment with liposomal amphotericin B was evaluated by using neutropenic mice with systemic candidiasis. Blood cultures of infected mice treated with different doses of liposomal amphotericin B were only positive at the early onset of the infection process and became sterile within 3 days; this was true even with mice treated with 1 mg of liposomal amphotericin B per kg of body weight that experienced a relapse of infection 14 days later. A significant correlation between presence of Candida albicans in the kidneys and PCR results obtained with blood was demonstrated. Thus, PCR results obtained with blood samples correlated well with the therapeutic efficacy of antifungal treatment.