Sialolithiasis is one of the most common diseases of salivary glands in middle-aged patients. Sialoliths are localized in submandibular glands in nearly 80% of the reported cases and they are classified as ‘giant’ in case any dimension exceeds 15 mm. Giant sialolith in submandibular gland is a rare disorder. Here, an unusual case of giant sialolith in submandibular gland is reported. A 42-year-old man referred with complaints of recurrent pain and swelling in the left submandibular area. Computerized tomography revealed a calcified mass of 42 × 17 mm size within the submandibular gland. Excision was performed in the submandibular gland and a giant sialolith of 35 mm length localized in the body of the gland was detected. The postoperative period was uneventful and the patient fully recovered.