Abstract: Based on perturbation theory and the idea of statistical associating fluid theory, an equation of state is established and is used to calculate the density of amino acid and sugar solutions. In the equation of state the induced dipole and quadrupole interactions between the particles are neglected. Density calculation of glycine, alanine, valine, amino n-butyric acid, serine aqueous solutions at four different temperatures and glucose, fructose, galactose, arabinose and xylose aqueous solutions at five different temperatures are made. In addition, this EOS is used to predict the density of amino acid + urea + H2O systems without any adjustable parameter. Results show that the accuracy of both regression and prediction calculations is high.