PURPOSE: The purpose was to examine the expression of nestin, Ki-67, and cyclin D1 in Müller cells after laser injury in adult rat retina. METHODS: The right eyes of adult Brown Norway rats were treated with laser photocoagulation. The eyes were removed 3, 7, and 14 days after laser treatment. The retinas were investigated immunocytochemically by confocal microscopy. Agarose-embedded sections were immunostained with antibodies to nestin, vimentin, glial fibrillary acidic protein (GFAP), glutamate-aspartate transporter (GLAST), rhodopsin, Ki-67, and cyclin D1. Cell death was examined using terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) assay on agarose sections. RESULTS: Nestin expression was induced in Müller cells following laser injury. In addition, Ki-67 and cyclin D1 expression was found in the nuclei of Müller cells after the treatment. TUNEL assay demonstrated that Müller cells were not labeled; hence these cells were not apoptotic. CONCLUSIONS: These results suggest that dedifferentiation and proliferation of Müller cells can be induced by laser injury in adult rat retina.