The most common type of actinomycosis is cervicofacial. Most of these reported cases present as indurated mass-like lesions. We report the first case of actinomycosis presenting as a giant ulcer eroding the tongue base. A 36-year-old man was seen with a progressive sore throat for 3 months. Laryngoscopy revealed a large ulcer (3 × 3 cm) on the right tongue base, vallecula, and part of right hypopharyngeal wall. A deep biopsy of the ulcer was performed, and histopathological study was compatible with the diagnosis of actinomycosis. Treatment was based on the diagnosis and penicillin V (500 mg 4 times daily) was given for 4.5 months. Symptoms resolved within 2 weeks and completely healing occurred by 4 weeks. No recurrence has been noted after follow-up of 36 months.