Objective To observe the expression of proinflammatory factors messenger RNA(mRNA) in periretinal membrane of proliferative vitreoretinopathy. Methods Fourteen specimens of periretinal membrane were collected during vitrectomy, and they were made into paraffin sections.The presence of mRNA coding for IL-1,IL-6,IL-8 and TNF alpha was observed by in situ hybridization(ISH) with biotin labeled oligonuclotide probes respectively.The eyeball after corneal grafting was made as normal control. Results No expression of proinflammatory factors mRNA was found in normal human retina.Positive staining was present in 5 specimens.In these specimens, IL-1βmRNA was found in 3 specimens and TNFαmRNA was found in 3 specimens,there is 1 specimen expressed IL-8 mRNA and 3 specimens expressed IL-6 mRNA.In these positive specimens, one contained cells expressing mRNA for IL-1βbeta and IL-6, and one exhibited cells expressing mRNA for IL-1β、IL-8 and TNFα,two membranes possessed positive cells for IL-6 and TNFαmRNA, one membrane contained IL-1βmRNA positive cells only. Conclusion These findings suggest that these cytokines may be locally produced by cells infiltrating epiretinal membranes. The expression of IL-1β, IL-6, IL-8 and TNFαmRNA within retinal membranes provides further evidence of a pathogenic role of these cytokines in proliferative vitreoretinopathy. (Chin J Ocul Fundus Dis, 2002, 18: 286-288)