  We report magnetic neutron-diffraction and electrical resistivity studies on
single crystals of the heavy-fermion antiferromagnet CeRhIn$_{5}$ at pressures
up to 2.3 GPa. These experiments show that the staggered moment of Ce and the
incommensurate magnetic structure change weakly with applied pressure up to
1.63 GPa, where resistivity, specific heat and NQR measurements confirm the
presence of bulk superconductivity. This work places new constraints on an
interpretation of the relationship between antiferromagnetism and
unconventional superconductivity in CeRhIn$_{5}$.
