Cross sections of the Fe-56(n, alpha) Cr-53 and Fe-54(n, alpha) Cr-51 reactions were measured at E-n = 5.5 and 6.5MeV and E-n = 4.0, 4.5, 5.5, and 6.5MeV, respectively, using a double-section gridded ionization chamber as the alpha-particle detector. Natural iron and enriched Fe-56 and Fe-54 foil samples were prepared. A deuterium gas target was used to produce monoenergetic neutrons through the H-2(d, n) He-3 reaction. Two rounds of experiments were performed at the 4.5-MV Van de Graaff Accelerator of Peking University. The foreground and background were measured in separate runs. The neutron flux was monitored by a BF3 long counter, and the cross sections of the U-238(n, f) reaction were used as the standard. Present results are compared with those of the TALYS-1.6 code calculations, existing measurements, and evaluations.