Polymerase chain reaction (PCR) was applied in order to improve the diagnosis of disseminated candidosis. A nested PCR technique with 2 primer pairs was used to increase the sensitivity. We were able to detect Candida DNA in serum and tissue samples from experimentally infected mice as well as in serum samples from candidemia patients and patients with deep-seated Candida infection. Our PCR could detect as little as 1 pg Candida albicans DNA. The PCR method was more sensitive than culture in both the mouse experiments and the patients with deep candidosis (5/7 were PCR positive and 0/7 blood culture positive), and of similar sensitivity in candidemia patients (11/17 were 15/17 blood culture positive). The relatively short processing time of PCR, when compared with culturing, its sensitivity, as well as the possibility of using serum samples for analysis, all helped improve the diagnostics in deep-seated candidosis and candidemia.