High-level ab initio calculations were carried out to estimate non-covalent interactions of systems based on pi interactions, namely, ion-pi, pi-pi, lone pair-or X-H ... pi interactions. It is important to obtain accurate geometric and energetic values since these interactions are present in relevant biological and chemical systems. The binding energies were calculated by means of the RI-MP2, SCS-RI-MP2 and CCSD( T) methods using the aug-cc-pVTZ and aug-cc-pVQZ basis sets. In principle, the most accurate methodology should give the most precise answer. However, the results obtained in this work indicate that the use of the most expensive computational method is not strictly necessary to achieve a good description of the above-mentioned non-covalent interactions. (C) 2011 Elsevier B.V. All rights reserved.