We examine the role of the large-scale anisotropy of the high-energy cosmic ray distribution in a search for the heavy decaying dark matter (DM) signal. Using recent anisotropy measurements from the extensive air shower (EAS) observatories we constrain the lifetime of the DM particles with masses 10 7 ≤ M X ≤ 10 16 GeV. These constraints appear to be weaker than that obtained with the high energy gamma-ray limits. We also estimate the desired precision level for the anisotropy measurements to discern the decaying DM signal marginally allowed by the gammaray limits and discuss the prospects of the DM search with the modern EAS facilities.Technically the heavy DM candidate X has two main parameters: mass M X and lifetime τ . Absolutely stable X-particles are not so interesting from the experimental point of view since its annihilation cross-section is bounded by unitarity: σ ann. X ∼ 1/M 2 X , which makes its indirect detection impossible for the todays experiments [30]. There are several sources of constraints for the heavy DM parameters. The mass is subjected to cosmological constraints [8,10,[31][32][33][34], and the lifetime of the DM particles can be effectively constrained with the observed fluxes of various high-energy particles or with the upper limit on these fluxes. For example, in Ref.[35] the constraints have been put using the shape of charged cosmic-ray spectra. However, with the modern cosmic ray data this method is not as effective in constraining τ as gamma-ray [27,[36][37][38][39] and neutrino [26,27] data.Another observable sensitive to the heavy DM decay is the cosmic-ray anisotropy. Apart from the DM searches, the anisotropy is a powerful tool for the elucidation of the cosmic-ray origin and propagation. In particular it is useful in study of the galactic magnetic field structure imprinted in cosmic rays [40][41][42][43] or in search for the extended cosmic-ray sources such as large scale structure [44][45][46][47]. While for TeV-PeV energies the existence of large-scale anisotropy has been confirmed by several experiments [48,49], for higher energies the deviations from isotropy are either not observed or have low significance [50][51][52][53][54][55]. In the present work we use the upper-limits on the cosmic ray flux anisotropy mentioned above to obtain the conservative constrains on the lifetime of the heavy DM with masses 10 7 ≤ M X ≤ 10 16 GeV. We use the parameters of DM allowed by the gamma-ray and neutrino limits to reveal the possible DM contribution to the anisotropy observables. This study complements our previous works [26,39], where constraints on the heavy decaying DM lifetime were obtained using the high-energy gamma-ray and neutrino flux upper limits.