Giant sialoliths larger than 20 mm are rare. The surgery has to be performed with the minimally invasive method in order to avoid the morbidity associated with the surgical techniques. In this report the surgical removal of a giant sialolith of 25 mm by using diode laser is described. A 57-year-old female was presented with a firm mass in the anterior part of the left side of the floor of the mouth. Following the clinical and radiological examination, the left submandibular duct sialolith was diagnosed. The diode laser was used with a power setting of 810 nm of wavelength, 4.0 W of power, 0.5 ms continuous wave and 1000 Hz of frequency for the incision. The giant sialolith was adequately removed under local anesthesia. The procedure was well-tolerated. The wound healing was uneventful in the postoperative period. By the 10th day after surgery the patient had no complaints and the salivary flow was normal. It was concluded that the use of 810-nm diode laser application is a safe and useful technique. Due to the excellent cutting and coagulation ability, there is a low complication rate, making it an appropriate alternative for this type of surgical procedure.