An extractive scintillating (ES) resin was evaluated for its performance as an on-line monitor of uranium in water. The TRU-ES resin is comprized of an inert macroporous polystyrene core impregnated with the organic fluors [diphenyloxazole (PPO) and 1,4-bis-(4-methyl-5-phenyl-2-oxazolyl)benzene (DM-POPOP)) and the selective extract (octyl(phenyl)-N, N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) in tri-butyl phosphate (TBP)]. The TRU-ES resin, packed into translucent FEP Teflon tubing, was placed into a flow-cell scintillation detection system. Acidified aqueous solutions, 233U spiked synthetic ground water and EPA natural uranium QA samples, were pumped through the flow-cell while gross count rate and pulse-height spectra were collected. The increase in count rate is attributed to the uranium being extracted from the aqueous medium and retained by the TRU-ES resin with simultaneous detection of the resultant scintillation photons. The TRU-ES loading efficiency was nearly quantitative out of 2M HNO3 with a flow rate of 0.5 ml . min-1. The detection efficiency was measured to be 51& for 233U. The detection limit was determined to be ~2 Bq . l-1 for 233U based on a resin free column volume of 0.2 ml, and 50 ml of 2M HNO3 acidified groundwater.