Stability studies play a critical role in assuring product quality at all points in the vaccine life cycle. These studies used to determine vaccine expiry date and vaccine efficacy. Accelerated stability and long term stability study performed for three batches of trivalent oral poliomyelitis vaccine (OPV) and three batches of monovalent OPV (type1) manufactured by Razi institute. After sampling, the samples tested intervals in months for long term stability and after 48h incubation in 37 0C for accelerated stability. All of quantitative and qualitative control tests including Potency, Sterility, Mycoplasma detection and Physicochemical testes performed in each period. Potency test for trivalent OPV (tOPV) in three batches of vaccines until 26 months and in two batches, until 27 months after production, met the specification. Potency test for monovalent OPV (mOPV) in all batches of vaccines until 18 month after production met the specification. Sterility, mycoplasma and physicochemical testes on these samples for mOPV and tOPV until expiry date and after that, passed. All batches of vaccines in accelerated stability met the specification after incubation and the reduction titer of vaccines was less than 0.5(-LogCCID50/dose). Results of this research indicated razi polio vaccines are stable for 24 months if the cold chain considered properly.