In the past twenty years, with the development of efficient computational methods, amino acids have been a permanent research target for theoretical chemists, not only because of their remarkable role in our lives (as components of proteins), but also because of their relatively small sizes, which render them suitable for an extensive range of theoretical investigations. We carried out computations on serine (Ser) and threonine (Thr) to understand the predominant intermolecular associations at their corresponding isoelectronic points (pI), using the hybrid method Hartree-Fock (HF) and density functional theory (DFT), B3LYP/6-31+G(d,p), as implemented in the Gaussian 03 program. In addition, we calculated Ser and Thr's chemical shifts, and compare our theoretical results to those acquired experimentally.