We report the low temperature magnetic properties of the DyScO$_3$ perovskite, which were characterized by means of single crystal and powder neutron scattering, and by magnetization measurements. Below $T_{mathrm{N}}=3.15$ K, Dy$^{3+}$ moments form an antiferromagnetic structure with an easy axis of magnetization lying in the $ab$-plane. The magnetic moments are inclined at an angle of $simpm{28}^{circ}$ to the $b$-axis. We show that the ground state Kramers doublet of Dy$^{3+}$ is made up of primarily $|pm 15/2rangle$ eigenvectors and well separated by crystal field from the first excited state at $E_1=24.9$ meV. This leads to an extreme Ising single-ion anisotropy, $M_{perp}/M_{|}sim{0.05}$. The transverse magnetic fluctuations, which are proportional to $M^{2}_{perp}/M^{2}_{|}$, are suppressed and only moment fluctuations along the local Ising direction are allowed. We also found that the Dy-Dy dipolar interactions along the crystallographic $c$-axis are 2-4 times larger than in-plane interactions.
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