Objective:To investigate the clinical and pathological features, treatment, and prognosis of gray zone lymphoma (GZL) .Methods:From July 2, 2013, to February 10, 2021, the clinical and pathological features, treatment, and outcomes of five patients with GZL at the Blood Diseases Hospital, Chinese Academy of Medical Sciences were studied retrospectively.Results:There were one male and 4 females, with a median age of 28 (16-51) years at diagnosis. Four patients had mediastinal (thymic) involvement, two of which had superior vena cava obstruction syndrome, and 3 patients had extra-nodal involvement. There was one case with a limited Ann Arbor stage and 4 cases with a progressive stage. Three patients had cHL-like pathomorphology with scattered Hodgkin-like cells, strongly positive for CD20, positive for CD30, and CD15 was negative; the other two patients had both cHL and DLBCL morphology, with some areas resembling Hodgkin cells and some areas resembling immunoblasts, strongly positive for CD30, and CD15 but negative CD20. Two patients were treated with cHL-like regimens for induction and achieved only partial remission; after salvage therapy with enhanced DLBCL-like regimens, all achieved complete remission (CR) . Three patients were treated with enhanced DLBCL-like immunochemotherapy regimens for induction, and two patients were effective, one of whom achieved CR. Four patients who did not achieve CR were given second or third-line salvage therapy, and all of them recovered. One patient lost parity, one died of disease progression at 35.9 months after diagnosis, and the remaining three maintained sustained remission.Conclusions:GZL is uncommon, usually affects younger patients, is mediastinal and is diagnosed using path morphology and immunophenotype. Patients with newly diagnosed GZL appear to be more sensitive to DLBCL-like immunochemotherapy regimens; relapsed or refractory patients were tended with non-cross-resistant combination chemotherapy or with new drugs.