One of the most common malformations of the tongue is fissured tongue, very often, is accompanied by geographic tongue; the etiopathogenesis of them is not known. The aim of study was to evaluate the prevalence of fungi in cases of fissured and geographic tongue, and to determine their species and susceptibility to selected antifungal drugs. The study included 104 patients with fissured and/or geographical tongue. To determine fungi present in the tongue, the material was collected with a sterile swab for mycological examination. The procedure was conducted according to that used at our Department. The in vitro susceptibility of the strains to nystatin and miconazole was evaluated. In 45 (43%) cases fissured tongue, in 28 (27%) geographic tongue, and in 31 (30%) both conditions were diagnosed. Mycological examination revealed fungi on the tongue in 73 (70%) patients, including 31 patients (69%) with fissured tongue, 19 (68%) with geographic tongue, and 23 (74%) with concomitant changes. The most frequently detected was Candida albicans (detected in 48-66% of cases); in individual cases, other species of Candida species were found. The strains demonstrated greater sensitivity to nystatin than to miconazole. An analysis of reported symptoms based on the presence or absence of fungi on the tongue revealed that idiopathic pain and burning were significantly more frequently reported by patients with fungi on the tongue (p = 0.034174). Statistically significant differences exist between the presence and absence of fungi with regard to the signs, symptoms of changes on the tongue (p = 0.026015). Also, statistically significant differences (p = 0.00000) exist regarding the presence of fungi with regard to brushing a fissured tongue, or a fissured and geographic tongue; fungi are frequently present when brushing is absent. The prevalence of fungi is greatest in patients with geographic tongue, especially those who do not brush the surface of the tongue.