In the present study, we attempted to diagnose and detect the extent of tumors in the sublingual region using magnetic resonance imaging (MRI) and dynamic MRI. MRI with or without gadopentetate dimeglumine (Gd-DTPA)enhancement in seven lesions of the sublingual regions was performed. The seven lesions included four cases of mucoepidermoid carcinoma (mucoepidermoid Ca), two cases of adenoid cystic carcinoma (ACC), and one case of squamous cell carcinoma (SCC). Whether the tumor was malignant or benign, as well as the differential diagnosis, could not be determined on the basis of the MR signals, even when enhancement was performed. Dynamic MRI was performed in five cases, two cases of ACC, two cases of mucoepidermoid Ca, and one case of SCC. The dynamic MRI showed a rapid enhancement at 30-45 sec in all five cases before the normal sublingual gland began to be enhanced. The early phases at 30-45 sec of the dynamic MRI in five cases showed marked enhancement before the normal sublingual glands were enhanced, and therefore could clearly show the extent of the lesions. In conclusion, the dynamic MRI may be useful in differentiating malignant from benign tumors, and in detecting the extent of the tumors in the sublingual carcinomas.