Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults and is associated with increased risk of malignancy. T-cell lymphoma associated with CLL has never been reported. The case report presents a unique case of peripheral T-cell lymphoma on the gingiva of a patient with CLL. A 66-year-old man with a history of CLL was referred to the Mayo Clinic, Department of Dental Specialties, for evaluation of swelling in the upper left posterior sextant. An intraoral examination revealed a soft tissue swelling in the area of teeth number 13 and 15, including the present edentulous ridge between number 13 and 15. An incisional biopsy was performed on the palatal aspect of tooth No. 15 and submitted for histologic evaluation. The histopathology revealed proliferation of large atypical cells beneath the epithelium, positive for antigens CD2, CD3, Beta-F1, TIA-1, and Granzyme B consistent for a diagnosis of a peripheral T-cell lymphoma. A team approach including the hematologist, general dentist and periodontist resulted in timely referrals leading to an early diagnosis and early intervention and treatment.