Nuclear quadrupolar resonance measurements find that, under hydrostatic or chemical pressure, the heavy fermion antiferromagnet CeRhIn5 becomes more itinerant and the Neel temperature T-N increases slightly at low pressures but decreases at large pressures. In CeRh0.5Ir0.5In5, unconventional superconductivity sets in well below T-N, with enhanced T(c)approximate to1 K. (C) 2003 Elsevier Science B.V. All rights reserved.