  We have analyzed the Swift data relevant to the high mass X-ray binary Swift
J1816.7-1613. The timing analysis of the BAT survey data unveiled a modulation
at a period of P_0=118.5+/-0.8 days that we interpret as the orbital period of
the X-ray binary system. The modulation is due to a sequence of bright flares,
lasting ~30 d, separated by long quiescence intervals. This behavior is
suggestive of a Be binary system, where periodic or quasi-periodic outbursts
are the consequence of an enhancement of the accretion flow from the companion
star at the periastron passage. The position of Swift J1816.7-1613 on the
Corbet diagram strengthens this hypothesis. The broad band 0.2-150 keV spectrum
is well modeled with a strongly absorbed power-law with a flat photon index
Gamma~ 0.2 and a cut-off at ~ 10 keV.
