  Numerous observations point towards the existence of an unknown elementary
particle with no electromagnetic interactions, a large population of which was
presumably produced in the early stages of the history of the Universe. This
so-called dark matter has survived until the present day, accounting for the
26% of the present energy budget of the Universe. It remains an open question
whether the particles comprising the dark matter are absolutely stable or
whether they have a finite but very long lifetime, which is a possibility since
there is no known general principle guaranteeing perfect stability. In this
article we review the observational limits on the lifetime of dark matter
particles with mass in the GeV-TeV range using observations of the cosmic
fluxes of antimatter, gamma-rays and neutrinos. We also examine some
theoretically motivated scenarios that provide decaying dark matter candidates.
