A major confounder of hepatic iron assessment by R2*-MRI is fat (e.g. steatosis) which introduces signal modulations. In this study, we systematically evaluate two signal modeling techniques, an autoregressive moving average (ARMA) model and the method provided by the ISMRM Fat-Water Toolbox for simultaneous iron and fat quantification in phantoms and in vivo. Preliminary data suggest that ARMA and Toolbox can be used for iron and fat quantification at 1.5T and 3T. In severe iron-overload cases, both, ARMA and the Toolbox might produce inaccurate FF results, however in vivo ARMA seemed to provide a more robust liver R2* quantification.