A simple and accurate spectrophotometric method for the determination of Yttrium using xylenol orange as a chromogenic dye in different rare earth concentrates of Egyptian monazite and xenotime by using direct and derivative spectrophotometric methods was described in the present work. The calibration curve was linear from 0.2 – 6 μg ml-1 at a maximum wavelength value of 568 nm. The various parameters and reaction conditions, which influence the formation of the complex, were investigated where the complex were stable for one hour. The molar absorptivity (є) and Sandell's sensitivity were found to be 3.4x104 L mol-1 cm-1and 2.7x10-3 respectively. The % RSD and percentage error were 1.64% and 1.5% respectively. A high sensitivity and accuracy for the determination of yttrium in the rare earths Elements (REE) concentrates was observed when the first derivative spectrophotometric method was applied.