We have measured the magnetic transition temperature as a function of pressure P up to about 14 kbar, and the lattice parameters a(T) and c(T) as a function of temperature T in the range 15 K<T<300 K, for CrMAs (M = Ni, Rh) with the Fe 2 P-type crystal structure. As P increases, the Curie temperature T C of CrNiAs, and the Neel temperature T N of CrRhAs, both decrease at low pressures, while at high pressures T C and T N exhibit deviations from linear pressure dependence in an upward convex and a downward convex fashion, respectively. In CrMAs (M = Ni, Rh), a(T) and c(T) show anisotropic thermal expansion around the magnetic transition temperature. The relation between the pressure dependence of the magnetic transition temperature T t r and the thermal expansion is consistent with the Ehrenfest relation with the pressure derivatives of T t r along the a- and c-axes. The nonlinear pressure dependences of T C and T N at high pressure are explained qualitatively in terms of the contribution of d-p covalent mixing between M and X atoms.