Signet ring cell lymphoma is a rare neoplasm characterized by large, vacuolated and clear cells mimicking mucin-producing adenocarcinoma. It is localized in nodal and extranodal sites. A case of a 59 years old male, with a diffuse lymphoma signet ring cell type localized on oropharyngeal mucosa is reported. The histopathology study showed signet ring cells and the immunophenotype was: vimentine(+), CD45(+), CD20(+), Ig M(+), Kappa chain(+) and high index proliferative activity of neoplastic cells (Ki 67:70%). After a review of the literature and previous reports, we could not find a similar case in this anatomic site. The patient had a unfavourable clinical course and died two months after the diagnosis without receiving any treatment.