Nuclear magnetic resonance on oriented nuclei was carried out using a sample of dilute 91Y and 91mY in iron prepared by ion implantation of radioactive precursor Rb isotopes. For 91YFe, the beta-ray asymmetry was utilized to measure the magnetic hyperfine interaction frequency, ν0=73.566(22) MHz, which led to the magnetic hyperfine field, BHF=-29.4(2)T, by using the known nuclear g-factor. The field shift of the resonant frequency, dν0/dB0=-2.501(17) MHz/T for 91YFe, implies a Knight shift value, K=0.0(8)%. The interaction frequency and the field shift of 91mYFe obtained via the gamma-ray detection confirmed the previously reported results. A ratio of the measured ν0 and dν0/dB0 values for both 91YFe and 91mYFe gave rise to the hyperfine anomaly, 91Δ91m=-4.2(8)%, which can explain discrepancies in the BHF values of YFe as determined by various experiments.