High-resolution neutron transmission measurements of natural iron have been performed in the fast neutron range from 100 keV to 12 MeV using the nELBE time-of-flight experiment at the Helmholtz-Zentrum DresdenRossendorf (HZDR) with a flight path of 868.34(30) cm. The measurements were carried out using three different iron samples of 20, 50 and 90mm thickness. The neutron transmission and effective total cross section were determined as a function of neutron energy, and the results were compared with existing evaluations and previous measurements. The measurements revealed significant shortcomings in the resolved resonance region of current evaluations, particularly in the energy range from 100 to 700 keV. The results of this work have already been used to improve the INDEN evaluation for the Fe-isotopes, which have been adopted by the ENDF/B-VIII.1 library and proposed for JEFF-4. The high-resolution time-of-flight measurements provide valuable new data for the development of more accurate nuclear data evaluations for natural iron.