Background: Geographic tongue is an inflammatory disorder of unknown etiology that affects the epithelium of the tongue. It has been associated with several cutaneous diseases. Objective: To determine the prevalence of geographic tongue and its association with other cutaneous diseases in patients referred to the dermatology clinic of Razi hospital. Patients and methods: A cross-sectional study was performed on all patients referred to one of the dermatology clinics of Razi hospital between February 21 and March 18, 1996 to determine the prevalence of geographic tongue and other diseases. Results: One-thousand and one-hundred and sixty referred patients were studied. The prevalence of geographic tongue was 6.2%. There was a statistically significant association between geographic tongue and seborrheic dermatitis (P=0.0053). Conclusion: Geographic tongue is associated with some cutaneous diseases. Detection of these associations could be a clue to the etiology and pathogenesis of geographic tongue.