FeSn is an antiferromagnet with the Néel temperature TN = 370 K, while CoSn is a Pauli paramagnet. We grew high-quality single crystals of FeSn and CoSn with the hexagonal structure and mainly studied the electronic state of FeSn by measuring the electrical resistivity, specific heat, magnetic susceptibility, magnetization, and de Haas–van Alphen (dHvA) effect. The Fermi surface properties of FeSn in the antiferromagnetic state were clarified by the dHvA experiment and energy band calculation. The main Fermi surface is found to be cylindrical along the hexagonal  direction, possessing a moderately large cyclotron mass mc 5:1m0 (m0: rest mass of an electron). The room-temperature resistivity ρRT of FeSn is anisotropic against the current direction, with ρRT = 75–175 µΩ·cm, revealing a usual magnitude, while the corresponding resistivity of CoSn is very small, ρRT = 4.5 µΩ·cm.