In this paper, we have discussed the C-13-{H-1} nuclear overhauser eff
ect (NOE) of amino acids in solids, and pointed out that the transient
NOE effect will occur when the C-13 Spin-lattice relaxation time (T1C
) is less than the proton spinlattice relaxation time (T1H). There are
four inequivalent methyls in L-isoleucine solid, and one of them unus
ually meets the condition of transient NOE effect. We have also discus
sed this fact in this paper.