By using quantum mechanical methods, ab initio molecular orbital computations have been carried out on a variety of small biologically active molecules. Since all living processes occur in the aqueous environment, it is necessary to investigate the effects of water solvation when exploring a biological molecule [Comput. Meth. Sci. Technol. 4 (1998) 25, J. Chem. Phys. 117 (2002) 4720]. First, the reactant complex of acetone and methylamine stabilized by water-mediated hydrogen bonding was studied. Then, ab initio characterization of the methyl phosphate interaction with water as well as its Ca 2+ , Mg 2+ , and Zn 2+ complexes [Biochemistry 41 (2002) 3207, Chem. Rev. 96 (1996) 2435, Chem. Rev. 101 (2001) 3] was completed. Finally, studies of phenol and N-Ac-l-Gly-NH-Me with inclusion of one water molecule as starting building blocks for future multi-molecular water solvation of these molecules have been completed. All the data has been generated at the RHF/3-21G level of theory using gaussian 98 computational program.