Background: In order to promote widespread adoption of appropriate clinical practice, the Italian Society of Hematology (SIE), and the affiliate societies SIES (Italian Society of Experimental Hematology) and GITMO (Italian Group for Bone Marrow Transplantation) established to produce guidelines in the most relevant hematological areas. In this article, we report the recommendations for management of T/NK-cell lymphomas, excluding mature T-cell leukaemias. Design: By using the Grades of Recommendations, Assessment, Development and Evaluation (GRADE) system, we produced evidence-based recommendations for the key clinical questions that needed to be addressed by a critical appraisal of evidence. The consensus methodology was applied to evidence-orphan issues. Results: Six courses of cyclophosphamide, doxorubicin, vincristine and prednisone (CHOP) or cyclophosphamide, doxorubicin, vincristine, etoposide and prednisone (CHOEP) chemotherapy were recommended for first-line therapy of patients with nodal, intestinal or hepatosplenic T-cell lymphomas (evidence: low; recommendation: do, weak). Except for ALK+ anaplastic large-cell lymphoma and elderly unfit patients, consolidation with high-dose chemotherapy was recommended (evidence: low; recommendation: do, weak). 50 Gy radiotherapy was the recommended first-line therapy for localized extranodal T/NK-cell lymphoma nasal type (evidence: low; recommendation: do, strong), while L-asparaginase-containing chemotherapy regimens were recommended for patients with systemic disease (evidence: very low; recommendation: do, strong). Conclusion: In adult T/NK-cell lymphomas, GRADE methodology was applicable to a limited number of key therapeutic issues. For the remaining key issues, due to lack of appraisable evidence, recommendations was based on consensus methodology.