An experimental study on the exchange bias properties of bulk polycrystalline Ni50Mn50−xSnx Heusler alloys has been performed. Martensitic transformations have been observed in the alloys for some critical Sn concentrations. The alloys, while in their respective martensitic phases, are found to exhibit exchange bias effect. Shifts in hysteresis loops of up to 225 Oe were observed in the 50 kOe field cooled samples. The observed exchange bias behavior in Ni50Mn50−xSnx is attributed to the coexistence of antiferromagnetic and ferromagnetic exchange interactions in the system.