We report the first Raman spectra of reduced nicotinamide adenine dinucleotide (NADH) when bound to an enzymatic active site, that of liver alcohol dehydrogenase (LADH). This was obtained by subtracting the Raman spectrum of LADH from that of the binary LADH/NADH complex. There are significant changes in the spectrum of bound NADH as compared to that in solution. The data indicate that both the nicotinamide moiety and the adenine moiety are involved in the binding. At least one of the two NH2 moieties of NADH also participates.