The anal. of 2-dimensional NOESY spectra can be misleading if spin diffusion effects are not properly taken into account. An approach consisting in suppressing spin diffusion by selective inversion of the spins undergoing the Overhauser effect, known as QUIET-NOESY (Zwahlen, C. et al., 1994), is described. In addn., the QUIET-EXSY method (Zwahlen, C. et al., 1995), related to the suppression of spin diffusion by QUIET-NOESY, is discussed. [on SciFinder (R)]