In this study, experiments were conducted to understand the effects of different quantities of additional iron on the fire assay of pyritic ores. Specimens were fused by using fluxes and PbO, which accumulates precious metals, with various quantities of iron. Both AAS and ICP were used to analyze the precious metals obtained. Correlation between the quantity of additional iron and the recovery of gold and silver was investigated. From the results, it was clear that the increase of additional iron quantity is responsible for the increase of recovery of lead, gold and silver amounts during the process.