The   physicochemical   properties of amino acids   in aqueous   solutionsprovide valuable information on solute-solute and solute-solvent interactions [1-6]. These interactions are important in understanding the stability of proteins, and are implicated in several biochemical and physiological processes in a living cell [7-9]. A.Ali and Shahajan[10] measured the density and viscosity and refractive index in aqueous tetrapropylammonium bromide containing Ɩ-leucine DƖ-alanine DƖ-valine and glycine for several concentrations of amino acids at different temperatures. A.Ali ,S. Khan and F. Nabi[11]  measured the density and viscosity and refractive index in aqueous glycerol containing Ɩ-leucine DƖ-alanine DƖ-valine, DƖ-α- amino-n- butyric acid and glycine for several concentrations of amino acids at different temperatures. In continuation of our earlier work[12,13], in the present article, we report the densities, ρ, viscosities, η, of   Ɩ-leucine in aqueous ethanol (1 to 10 wt. % of ethanol, w/w in water) at 298.15, 303.15, 308.15, 310.15, and 313.15 K. Experimental data have been used to calculate, apparent molar volume,_, limiting apparent molar volume,  and the slopes, S_v, transfer volumes, , Falkenhagen Coefficient, A and Jones – Dole coefficient, B. These parameters have been used to discuss the solute-solute and solute-solvent interactions in these systems.