Abstract: Bone marrow involvement (BMI) is a hallmark of poor prognosis of non-Hodgkin's lymphoma. Because of its pivotal role in assessing prognosis and guiding treatment, it is an essential assessment for(NHL) first-time referrals of NHL. In its detection method, bone marrow biopsy (BMB) possesses the position of cornerstone. However, flow cytometry, cytogenetics and molecular biology of aspirate also have increased their diagnostic significance and have showed new value of assessing the prognosis with the development of technology. At the same time, PET-CT, as an effective detection method, has gradually become a research hotspot. This article reviews these detection methods and recent BMI prognostic studies, and looks forward to future of this field.