  We present anisotropic thermal expansion measurements on single crystalline
ErNi2B2C. All three, superconducting, antiferromagnetic and weak ferromagnetic
phase transitions are unambiguously distinguished in the data. Anisotropic
uniaxial pressure dependencies of the transitions are estimated based on the
Ehrenfest relation, leading to a conclusion, in particular, that weak
ferromagnetic state will be suppressed by small, order of several kbar,
hydrostatic pressure.
