The aim of this study was to examine the potency of fibroblast cells transdifferentiated to neuron cells in vitro. Newborn rat neuron conditioned medium (NBRN CM) was collected from neuron cells cultured with mDMEM without serum for 48 hours. Fibroblast cells werecollected from fetal rat muscle treated with trypsin. Fibroblast cells were culture with 3 kind of culture medium: mDMEM + 0.01 mM β-mercaptoethanol; mDMEM + 50% NBRN-CM and mDMEM + 0.01 mM β-mercaptoethanol + 50% NBRN CM . As control, cells was culturedwith mDMEM +10% newborn calf serum (NBCS). The addition of NBRN CM into culture medium resulted in 12.97% newborn cells in fibroblastculture medium passage I. Newborn rat neuron conditioned medium in fibroblast culture medium resulted 12.97% neuron cells at passage 1. Thepercentage was increased (14.60%) when β- mercaptoethanol added into medium. The same result was found at passage 3 (12.67%; 13.17%). Itshowed that fibroblast cells has potency to transdifferentiated into neuron cells when cultured with NBRN CM. Further research is needed toknow the fibroblast transdifferentiation potency.Key words: fibroblast, transdifferentiation, conditioned medium, neuron cells, in vitro