A detailed study on the role of interface structure and magnetism in magnetoresistance (MR) in Fe/Au multilayers has been carried out. Two series of multilayers were deposited on Si substrate by sputtering: one series with varying Fe layer thickness, t_Fe=30–100 Å, and another series with varying Au layer thickness t_Au= 50–150 Å. MR measurements were done using a 4-probe technique. The multilayer interface structure and magnetic properties were studied by specular X-ray reflectometry and polarized neutron reflectometry (PNR). Details of the interface fractal morphology were obtained from diffuse X-ray reflectivity (DXRR). Bulk magnetic measurements were carried out on a superconducting quantum interference device magnetometer. Change in MR can be associated with magnetic and morphological properties of Fe/Au and Au/Fe interfaces in Fe/Au multilayer samples as obtained by reflectometry. Large MR is also associated to interfaces with larger magnetization, large in-plane correlation length and higher Hurst parameter, obtained from PNR and DXRR.