During the process of drug discovery, INPHARMA can be used to derive the structure of receptor/lead compound complexes binding to each other with a K(d) in the microM to mM range. To be successful, the methodology needs adjustment of various parameters that depend on the physical constants of the binding event and on the receptor size. Here we present a thorough theoretical analysis of the INPHARMA interligand NOE effect in dependence of experimental parameters and physical constants. This analysis helps the experimentalist to choose the correct experimental parameters and consequentially to achieve optimal performance of the methodology.