Viscosity coefficients of L-phenylalanine, L-leucine, L-glutamic acid, or L-proline in 2.0 mol.dm(-3) aqueous NaCl or 2.0 mol dm(-3) aqueous NaNO3 systems have been determined as a function of molal concentrations of amino acids at temperatures of (298.15, 303.15, 308.15, 313.15, 318.15, 323.15, and 328.15) K. Viscosity coefficients vary linearly with an increase in molal concentration of the amino acids. The trends of variation of viscosity values with an increase in molal concentration of L-phenylalanine, L-leucine, L-glutamic acid, and L-proline in 2.0 mol dm-3 aqueous NaCl and 2.0 mol dm-3 aqueous NaNO3 solutions and with an increase in temperature have been ascribed to the solute-solvent interactions operative in the solutions. The computed Jones-Dole B-coefficients have been also interpreted in terms of solute-solvent interactions.