The results of quantum chemical computations of first-order hyperpolarizability (beta) of urea molecule in the gas phase and in polar solvents are presented. The environmental effects were included via the quantum-mechanical Langevin dipoles/Monte Carlo (QM/LD/MC) method as well as supermolecule approach. The results of calculations confirm the existense of the substantial solvent effect on beta value for urea molecule. The calculated beta values, including solvent effect, are compared with experimental data determined in solution phase by EFISH measurements. (C) 2002 Elsevier Science B.V. All rights reserved.