In this paper, a novel method was developed for the precon- centration, separation, and deter- mination of light (Ce), medium (Eu and Gd), and heavy (Yb) rare earth elements (REEs) by induc- tively coupled plasma mass spec- trometry (ICP-MS), based on the adsorption of Ce3+, Eu3+, Gd3+, and Yb3+ on carbon nanofibers (CNFs) loaded with 1-phenyl-3- methyl-4-benzoyl-5-pyrazone (PMBP). The REEs can be adsorbed quantitatively on CNFs- PMBP in the pH range of 5.0 to 8.0 and then eluted completely with 1.0 mol L-1 HNO3. The experimental parameters for the preconcentration and separation of REEs, such as pH, sample flow rate / volume, eluent concentra- tion / volume, and interfering ions, were examined in detail. Under optimum conditions, the detection limits of this method were found to be 1.5, 0.9, 0.5, and 0.3 pg mL-1 for Ce, Eu, Gd, and Yb, respectively, and their relative standard deviations were less than 5% (c=1.0 ng mL-1, n=9). This method has been applied to the determination of trace REEs in a natural water sample and a certified reference material, GBW 07602 (GSV-1) Combined Sample of Shrub Branch and Leaves, with satisfac- tory results.