The nuclear magnetic resonance frequency of the F19 nucleus in antiferromagnetic MnF2, in zero external field, has been measured as a function of pressure at 4.2°K, 20.4°K, and 35.7°K using a new type very high frequency variable frequency spectrometer. From these measurements we have deduced the pressure dependence of the hyperfine coupling constant (A) between the manganese electrons and the fluorine nucleus, and the pressure dependence of the Néel temperature. This deduction gives (1A)(dAdP)=+(1.9+/-0.1)×10-6/(kg/cm2) and (1TN)(dTNdP)=+(4.4+/-0.3)×10- 6/(kg/cm2). We have also measured the compressibility of MnF2. The magnitude and pressure dependence of A is explained using the theories of Mukherji and Das, and Marshall and Stuart, which permit a calculation of the dependence of A on the interatomic distances, starting from the Hartree-Fock self-consistent field wave functions for Mn2+ and F- with the Mn2+ wave functions properly adjusted to bring it into agreement with neutron scattering form factor measurements. The theory is in very good agreement with the experimental results.