The influence of the milling and annealing conditions on the structural evolution of mechanically-milled SmCo5/alfa-Fe (20 and 30 wt %) and (Nd0.92Dy0.08)2Fe14B/ alfa -Fe(22 wt% ) nanocomposites has been studied. The structural evolution of the samples was followed by X-ray diffraction, electron microscopy and Mössbauer spectrometry. The width of the diffraction peaks increases with milling time, then the Bragg peaks almost disappear for high milling times. The characteristic diffractions peaks of the SmCo5-type phase are restored during subsequent heat treatment and the XRD patterns show also the presence of the Sm2(Co, Fe)17 phase induced by milling. XRD peaks of (Nd0.92Dy0.08)2Fe14B/ alfa -Fe composite can be attributed to R2Fe14B and alfa -Fe phases. No additional peaks were observed.