In this paper, the process of simultaneous determination of 15 rare earth elements has been investigated by ICP-MS method. The method showed good performance in the linear concentration ranges from 3 to 105 ppb. The LODs were lower than 3.2 ppb. The LOQs were lower than 10.8 ppb. Spike recoveries were from 95 to 99% and the repeatabilities were lower than 11% RSD. The optimal decomposition time is 4 hours at decomposition temperature of 250 °C for all basnasite, monazite and xenotime ore samples by using the microwave digestion.The method has been applied successfully for investigation and exploration of basnasite, monnazite and xenotime ore samples
