The anisotropic physical properties of single crystals of orthorhombic PtSn4 are reported for magnetic fields up to 140 kOe, applied parallel and perpendicular to the crystallographic b axis. The magnetic susceptibility has an approximately temperature-independent behavior and reveals an anisotropy between the ac plane and b axis. Clear de Haas-van Alphen oscillations in fields as low as 5 kOe and at temperatures as high as 30 K were detected in magnetization isotherms. The thermoelectric power and resistivity of PtSn4 show the strong temperature and magnetic field dependencies. A change of the thermoelectric power at H=140 kOe is observed as high as ≃50 μV/K. Single crystals of PtSn4 exhibit very large transverse magnetoresistance of ≃5×105% for the ac plane and of ≃1.4×105% for the b axis resistivity at 1.8 K and 140 kOe, as well as pronounced Shubnikov de Haas oscillations. The magnetoresistance of PtSn4 appears to obey Kohler's rule in the temperature and field range measured. The Hall resistivity shows a linear temperature dependence at high temperatures followed by a sign reversal around 25 K which is consistent with thermoelectric power measurements. The observed quantum oscillations and band structure calculations indicate that PtSn4 has three-dimensional Fermi surfaces.