In this work a method is proposed for calculation of the quaternary eutectic using data from binary and ternary systems, The eutectic is determined from the intersection of the four surfaces of primary crystallization of the components. The equations were examined for the system Cd-Pb-Sn-Bi. As the presence of the perutectic compound Pb3Bi has essentially no influence on the liquidus surface, pure Bi (1), Pb (2), Sn (3) and Cd (4) were used as components of this system. The calculated and experimental values of the fusion temperature and composition of the quaternary eutectic are compared below : [GRAPHICS] Good agreement is observed between the calculated and experimental values of the coordinates of the quaternary eutectic.