Abstract.We analyze the distribution of Abell clusters of galaxies to study the regularity of the supercluster-void network. We apply a new method, the regularity periodogram, that is sensitive to the geometry of the location of clusters, and measure the regularity of the network. We find that the supercluster-void network resembles a cubic lattice over the entire volume considered (out to the distance of 350 h −1 Mpc). The distribution of clusters in rich superclusters is not isotropic: it is periodic along a cubic lattice approximately aligned with the supergalactic coordinates S GX, S GY, S GZ. This large-scale inhomogeneity does not contradict recent CMB data, but its theoretical explanation remains a challenge.

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