Neural tissue encoding protein with EGF-like repeats (NELL1) is a recently discovered target antigen in membranous nephropathy (MN). The initial study showed that most cases of NELL1 MN had no underlying disease associations, i.e. most cases of NELL1 MN were classified as primary MN. Subsequently, NELL1 MN has been found in the setting of various diseases. These include NELL1 MN associated with malignancy, drugs, infections, autoimmune disease, hematopoietic stem cell transplant, de novo MN in a kidney transplant and sarcoidosis. Thus there is marked heterogeneity in the diseases associated with NELL1 MN. Evaluation of an underlying disease associated with MN will likely need to be more exhaustive in NELL1 MN.