While the mortality impacts of urban air pollution have been well addressed in the literature, very little is known about the mortality impacts and associated social cost from wildfire-smoke exposure (Kochi et al., 2010; U.S. Environmental Protection Agency, 2004). In an attempt to address this knowledge gap, we estimate the social cost associated with excess mortality due to smoke exposure during the 2003 southern California wildfires. Accounting for confounding factors such as seasonality and fluctuation of daily mortality levels, we identify 133 excess cardiorespiratory-related deaths caused by wildfire-smoke exposure. The mean estimated total mortality-related cost associated with the 2003 southern California wildfire event is approximately one billion U.S. dollars. Accounting for mortality costs associated with wildfire-smoke exposure allows for a better understanding of the tradeoffs associated with fuel treatment programs and suppression costs.