The swift heavy ion irradiated La0.9Mn0.8Fe0.2O3 (La-deficient) system with 200 Mev Ag16 + ion beam at fluence 5 × 1012 ions/cm2 was studied with X-ray diffraction (XRD) and Mössbauer spectroscopic measurements. Comparison of Mössbauer parameters with those of unirradiated sample showed an increase in line width on irradiation which may be due to reduction in particle size as well as due to creation of defects. An increase in quadrupole splitting with no appreciable change in isomer shift showed ion-induced structural disorder in the material after irradiation. An attempt is made to compare the effect of fluence with the hydrostatic pressure on the sample.