The first-order spin-reorientation transition in the Mn-substituted yttrium orthoferrites, YFe1xMnxO3 (x=0.1, 0.15 and 0.2), has been investigated using 57Fe Mössbauer spectroscopy. Owing to its large anisotropy, substitution of Mn3+ ions in YFeO 3 induces a spin-reorientation transition from the low-temperature antiferromagnetic state to a high-temperature weak ferromagnetic state. With increasing x, the spin-reorientation transition temperature (TSR) increases whereas the Néel temperature (TN) decreases. Analysis of the Mössbauer spectra unambiguously confirms the occurrence of spin reorientation relative to crystal axes. At a given temperature, the mean hyperfine field decreases with the increasing Mn concentration. The variation of canting angle with temperature for YFe0.85Mn0.15O 3 has been estimated. © 2011 IOP Publishing Ltd.