This study was undertaken to investigate the interaction between uranium contaminated seawater and the sand in contact with this seawater. Adsorption data have been evaluated from column experiments of seawater from Marmara, Black Sea and Mediterranean contaminated with 10(-7) M uranium. The uranium uptake on the fractionated and non-fractionated sand of these sea have been measured as a function of time. The adsorption proceeds via a rather fast stage followed by a slower one. Results could be correlated with particle size and porosity of the sand. Adsorption isotherms are also derived from amount of adsorbed uranium vs. time plots and the results have been analyzed by the Langmuir, Freundlich and Dubinin-Radushckevich (D-R) isotherm equations over the entire range of uranium concentrations. By fitting the data to D-R isotherm, we have calculated the adsorption energy and decided to type of the adsorption.