Systemic mycoses and their oral manifestations are very rare. We present a case of a 60-year-old man with an ulcerated lesion on the lateral border of the tongue. Histologic studies revealed a granulomatous fungal infection by Coccidioides immitis. After pharmacological treatment, the lesion resolved. Recently, northern Mexico has been reported to be an endemic zone of C. immitis infections; therefore it should be considered in the differential diagnosis of mouth lesions. A comprehensive clinical history, physical exploration, and complementary studies are essential for an accurate diagnosis.