The pathogenic mechanisms of epiretinal membranes are not clearly understood nowadays in ophthalmology. Trying to elucidate it from another aspect, we examined the presence of HLADR antigen in 41 epiretinal membrane specimens from patients with proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR) by using immunohistochemical technique (APAAP). The results showed that 82.93% of the membranes (34 out of 41) were HLA-DR antigen positive. HLADR antigen was considered to be expressed by macrophages in epiretinal membranes. The findings here reveal that the formation and development of epiretinal membranes are probably correlated with immune responses.