AIM: To investigate the role of retinal pigment epithelium (RPE) in the growth of Müller cells using a co-culture system in vitro. METHODS: Müller cells were co-cultured with RPE cells under both normoxic and hypoxic conditions in Transwell chamber culture system. Müller cell proliferation was eval- uated by MTT assay. The number of cells that migrate through micropores and stay on the outer bottom side of insert systems were observed and counted. RESULTS: The activities of proliferation and migration of Müller cells when co-cultured with RPE cells were significantly higher than those of the Müller cells when cultured alone at all time points under both normoxic and hypoxic conditions. However, for both the co-culture and control groups, there was no significant difference between the measurements at 3 and 6 hours. CONCLUSION: Evidence suggests that RPE, when co- cultured with Müller cells, can stimulate migration and prol- iferation of Müller cells under both hypoxic and normoxic conditions in a time-dependent manner; however, there is no evidence to support the synergetic interaction of RPE and Müller cells co-cultured under hypoxic conditions.