Hydrostatic pressure up to 10 GPa has been applied to determine the lattice compressibility and the dependence of transition temperature ${T}_{c}$ of an ${\mathrm{MgB}}_{2}$ superconducting material that shows a very narrow transition range when prepared by high-pressure sintering. The transition temperature ${T}_{c}$ decreases with increasing pressure at a rate of 1.03 K/GPa. The material has a bulk modulus 172 GPa and the unit cell of the ${\mathrm{MgB}}_{2}$ crystals shows an anisotropic compressibility with its c axis appearing more compressible than the $a/b$ axis. The experimental results are discussed within the framework of the BCS theory, which gives rise to estimates in good agreement with the experimental results.