Oseltamivir and zanamivir are well-established and well-researched drugs for the treatment of influenza in Japan and the rest of the world. A new neuraminidase inhibitor, laninamivir octanoate, has been approved for use in Japanese clinics. Laninamivir octanoate is an inhaled drug with unique characteristics. The inhaled laninamivir octanoate is converted into its active form, laninamivir, in the lungs where a high concentration persists for a long period of time. The concentration of laninamivir exceeds the level necessary for influenza virus replication inhibition for at least 5 days, thus influenza can be treated with a single administration. The drug is delivered using one device requiring four inhalations for children and two devices requiring eight inhalations for adults. Clinical trials have shown comparable efficacy for laninamivir octanoate and oseltamivir. Laninamivir octanoate also displayed a sufficient antiviral effect to treat infection with H275Y-mutated oseltamivir-resistant virus. Laninamivir octanoate has displayed clinical efficacy comparable to that of oseltamivir and zanamivir against the H1N1 pandemic influenza strain from 2009, seasonal H3N2 influenza and influenza B viruses. The prophylactic efficacy of laninamivir octanoate has been shown in animal models. The effectiveness of laninamivir against the highly pathogenic avian influenza virus H5N1 has also been shown in vitro and in animal models. A major clinical benefit of this drug is that the single administration is very convenient for both the patient and doctor, which leads to improved compliance. Furthermore, this drug shows promise for the treatment of influenza in future pandemics.