For diagnostic purposes it is normally not important to obtain a biopsy specimen, since an oral smear from the lesion will yield blastospores and pseudohyphae in abundance. However, in lesions that respond poorly to antimycotic treatment a biopsy should be carried out to detect possible malignant changes in the epithelium. Assessment of cell-mediated immunity againstCandida albicansand other antigens may be important in patients with severe chronic candidosis to assess the degree of immunocompetence and prognosis. Usually, patients with oral candidosis show only moderately elevated antibody titers in serum and saliva againstC. albicans, and serologic tests are normally not a diagnostic tool for oral candidosis. However, such tests may be a prognostic instrument in patients with severe oral candidosis who respond poorly to antimycotic therapy.