First principles calculations for rare earth compounds PrSb and PrBi in NaCl(B1), CsCl(B2), ZB(B3), WC(Bh) and CuAu(L1 o) structures have been performed using density functional theory within the generalized gradient approximation. For the total-energy calculation, the projected augmented plane-wave implementation of the Vienna ab-initio simulation package has been used. Our structural results are consistent with the available experimental and other theoretical data. The phonon dispersion curves and corresponding one-phonon density of states (DOS) for both compounds are also computed in NaCl(B1) structure which is energetically more stable than the other structures. In addition to these properties, the temperature/pressure variation of the volume, thermal expansion coefficient, heat capacity are calculated in over wide pressure and temperature ranges.