  We report the synthesis of EuPtIn$_{4}$ single crystalline platelets by the
In-flux technique. This compound crystallizes in the orthorhombic Cmcm
structure with lattice parameters $a=4.542(1)$ \AA, $b=16.955(2)$ \AA$\,$ and
$c=7.389(1)$ \AA. Measurements of magnetic susceptibility, heat capacity,
electrical resistivity, and electron spin resonance (ESR) reveal that
EuPtIn$_{4}$ is a metallic Curie-Weiss paramagnet at high temperatures and
presents antiferromagnetic (AFM) ordering below $T_{N}=13.3$ K. In addition, we
observe a successive anomaly at $T^{*} = 12.6$ K and a spin-flop transition at
$H_{c} \sim 2.5$ T applied along the $ac$-plane. In the paramagnetic state, a
single Eu$^{2+}$ Dysonian ESR line with a Korringa relaxation rate of $b =
4.1(2)$ Oe/K is observed. Interestingly, even at high temperatures, both ESR
linewidth and electrical resistivity reveal a similar anisotropy. We discuss a
possible common microscopic origin for the observed anisotropy in these
physical quantities likely associated with an anisotropic magnetic interaction
between Eu$^{2+}$ 4$f$ electrons mediated by conduction electrons.
