Purpose: Primary adrenal lymphoma is extremely rare. We analyzed our cases to further illustrate the clinical characteristics of this rare disease.Methods: In the past 10 years, there have been three patients diagnosed as primary adrenal lymphoma in our institution. There have been another three patients with secondary adrenal lymphoma, involving not only the adrenal glands but also other organs or lymph nodes. The clinical and pathological characteristics of the six cases were compared and analyzed.Results: The three cases of primary adrenal lymphoma were characterized with old age, male-predominance, bilateral adrenal involvement, adrenal insufficiency, and histological type of diffuse large B-cell lymphoma. All of them received chemotherapy but died within half year of diagnosis: one died of disease progression; the other two died of complications. The three cases of secondary adrenal lymphoma were relatively young. All had unilateral adrenal involvement and no adrenal insufficiency. The pathological examinations revealed diffuse large B-cell lymphoma. The prognosis was better: two of them have been disease-free after treatment; the other died of disease progression.Conclusions: Primary adrenal lymphoma is extremely rare. It predominantly affects the elderly and men, mostly involves the bilateral adrenal glands, and usually causes adrenal insufficiency. The majority of the cases are of diffuse large B-cell lymphoma. The prognosis is poor, and most patients die within one year of diagnosis. With very limited experience, the optimal therapeutic strategy remained unclear and required further studies. It is important to differentiate between primary and secondary adrenal lymphoma since the clinical course is extremely different.