The hyperfine magnetic field (hmf) at nonmagnetic cadmium impurity in L21 Heusler alloys Rh2MnGe (Tc=450 K) and Rh2MnPb (Tc=338 K) has been measured as a function of temperature by Time Differential Perturbed Angular Correlation (TDPAC) technique. Measurement utilized the 84-nsec 247-keV state (μ=−.7656 nm) in Cd-111 populated in the decay of 2.8-d In-111. Alloys were prepared by substituting for 2 atomic % of Ge or Pb by In metal which had been bombarded with 30-MeV protons. The measured hmf’s in kG at cadmium impurity, presumed to be at Ge or Pb site, are (with temperatures in parentheses) in Rh2MnGe 188±6 (77 K) and 160±3 (293 K); and in Rh2MnPb 143±2 (77 K), 114±2 (200 K), 84±2 (273 K) and 53±1 (293 K).