Purpose: Macrophages are versatile cells and have been known as a cellular component of epiretinal membranes of proliferative intraocular disorders (PID). However, the origin and functions of these cells in the membranes are not yet clear. In the present study we investigated the characterization of macrophages/monocytes in various types of human epiretinal membranes from patients with proliferative vitreortinopathy (PVR) , proliferative diabetic retinopathy (PDR) and ocular perforating injury by means of immunohistochemical techniques. Methods: A total of 49 epiretinal membranes of PID in which 24 were PDR specimens, 17 were PVR and 8 were proliferations after perforating eye injury were studied. Monoclonal antibodies against human macrophages, monocytes, HLA-DR antigen and interleukin-1 (IL-1) were used. The alkaline phosphatase anti-alkaline phosphatase (APAAP) technique was performed.Results: The results showed that 19 out of 24 PDR specimens (79%), 15 out of 17 PVR specimens (88%) and 7 out of 8 tr Purpose: Macrophages are versatile cells and have been known as a cellular component of epiretinal membranes of proliferative intraocular disorders (PID). However, the origin and functions of these cells in the membranes are not yet clear. In the present study we investigated the characterization of macrophages / monocytes in various types of human epiretinal membranes from patients with proliferative vitreininopathy (PVR), proliferative diabetic retinopathy (PDR) and ocular perforating injury by means of immunohistochemical techniques. Methods: A total of 49 epiretinal membranes of PID in which 24 were PDR specimens, 17 were PVR and 8 were proliferations after perforating eye injury were studied. Monoclonal antibodies against human macrophages, monocytes, HLA-DR antigen and interleukin-1 (IL-1) were used. The alkaline phosphatase anti-alkaline phosphatase Results showed that 19 out of 24 PDR specimens (79%), 15 out of 17 PVR specimens (88%) and 7 out of 8 tr