Objective: Given some failures of the Capital Asset Pricing Model in explaining the default risk anomaly, some researchers have claimed the two-beta model, established by Campbell and Vulteenaho (2004), is functionally able to explain this peculiarity. Originated primarily from CAPM, two-beta model decomposes the market beta to the discount-rate beta and the cash-flow beta. In other words, the two beta model decomposes the systematic risk to the discount-rate and cash-flow risk. Method: In an attempt to test the ability of the model to explain the anomaly in the Tehran Sthock Exchange, we firstly ranked firms based on their default risks, measured by Ohlson’ s (1980) model, and then employed the two-beta model to decompose the market beta to discount-rate beta and cash-flow beta. We, ultimately, applied a simple regression model to extract the discount-rate risk premium and cash-flow risk premium. Results: Our results reveal that as the default risk increases, the discount-rate beta increases and the cash-flow beta decreases. Furthermore, the cash-flow risk premium is significantly more than the discount-rate risk premium. Therefore, the two-beta model can explain the anomalous default risk existing in the Tehran Exchange Security.