The threat of an influenza pandemic has led many countries to build up stockpiles of antiviral drugs, particularly oseltamivir, which can be used both for prevention and treatment. Several recent studies, based on mathematical modeling, have examined the impact of large-scale use of this drug to control an emerging pandemic, slow its spread within a country, or limit its epidemiological impact. They conclude that the combination of using antivirals for ring prophylaxis around the first cases, combined with social distancing measures, could help control the initial transmission clusters of a virus with pandemic potential, provided that the virus has moderate transmissibility and that control measures are implemented very rapidly and with broad coverage. In the event of failure, these same strategies could delay the spread of the virus within a country. The use of antivirals for curative treatment should substantially reduce the epidemiological impact of the pandemic, and even the proportion of the population affected, assuming that curative treatment reduces the duration of the infectious phase. These findings support the establishment of antiviral stockpiles intended to cover, at a minimum, the needs for treating cases and, ideally, to contribute to the international effort to control the first epidemic outbreaks and intervene in the early stages of local transmission chains, in order to slow the national spread of the virus. These results are contingent on the efficacy of oseltamivir against the pandemic virus and confirm the importance of sensitive and responsive epidemiological surveillance.