AbstractSome compositions of Ni-Mn-X (X = Ga, In, Sn) ferromagnetic shape memory alloys exhibit a first order magnetostructural phase transition. Magnetic entropy change ΔSm in the vicinity of this transition has been studied by magnetization and heat capacity measurements. Comparison of these results point to a large difference in magnitudes of ΔSm obtained from magnetization and heat capacity data. It is suggested that this discrepancy originates from overestimation of \Delta S_m determined from the magnetization measurements and underestimation of ΔSm obtained from the heat capacity measurements.