The phosphorus distribution ratios between carbon-saturated iron melts and Na2O-SiO2, Na2O-SiO2-MO (M=Mg, Ca, Ba), CaF2-CaO or CaF2-CaO-Al2O3 slags have been obtained as a function of slag compositions and temperatures. The phosphorus distribution ratios in the Na2O-SiO2-MO (M=Ca, Ba, Mg) system were found to decrease when Na2O was replaced by MgO, CaO and BaO at a constant SiO2 content. The temperature dependence of phosphorus distribution ratios in the CaF2-CaO and CaF2-CaO-Al2O3 systems has been observed in the temperature range of 1 430°C to 1 550°C, while in the Na2O-SiO2 system it has not been observed at 1 250°C and 1 350°C. The phosphorus distribution ratios in the MF2-MO (M=Mg, Ca, Ba, Na) system were found to decrease in the order of Na>Ba>Ca>Mg.