The lattice deformation of a Bi-2212/Ag tape conductor is investigated as a function of an externally applied strain at 300 K. This macroscopic strain is applied in the same direction (¿axial¿) as where the current is normally passed through the conductor. A small but significant shift is observed in the position of the diffraction peak. In a limited strain regime this shift is proportional to the applied strain. The deformation of the c-axis that corresponds to the observed peak shift can be described well with an elastic grain deformation. For tensile axial strains above 0.2% and below ¿0.1% strain, the c-axis deformation is limited to an almost constant value. These two limits in the elastic behaviour divide the axial strain range into three regimes. A good correlation with the axial strain dependence of the critical current at 77 K, is obtained when the thermal contraction is taken into account. In the central strain range, where an elastic lattice deformation is observed, the critical current remains almost constant. Any tensile or compressive deformation that exceeds the elastic limits causes a more severe and irreversible reduction of the critical current.