Sialolithiasis account for the most common disease of salivary glands. The majority of salivary gland calculi involve the submandibular duct and rarely in its parenchyma. This is common benign disease may cause the acute or chronic sialadenitis. Sialolith can be single, multiple, unilateral or bilateral. Patient can presents with history of swelling and pain. Giant sialolithiasis is not a common condition mainly occur in submandibular duct. Here we discuss the unusual giant submandibular duct calculus in adult male patient, its Computed Tomography (CT) scan appearance and post-surgical findings.