A method for the determination of rare earth elements at chondritic abundance levels is described. Dissolution of rock samples is accomplished by sodium peroxide fusion. Rare earth elements are separated from matrix concomitants and pzeconcentrated by canon exchange employing No. 1 resin. The analysis of the samples is performed on a Jarrell-Ash model 1160 Atom- Comp spectrometer with 60 channels. A DEC PDP 11/23 minicomputer controls the ICAP spectrometer and is interfaced to a LA-120 DECwriter for data reporting. A precision of 1-5.5%(RSD) was attained. Analyses of several hun- dreds of rock samples showed that the method is well suited to the routine simultaneous determination of 15 rare earth elements.