The spin–lattice relaxation times (T1) of the twelve most abundant carbon atoms in acetylated milled wood lignin (MWL) from hazelnut (Corylus avellanus) have been determined by the progressive saturation pulse Fourier transform (PSFT) technique. T1values below 0.5 s have been found for the aliphatic carbon atoms in the C3side chains, while substituted aromatic, carbonyl and CH3carbon atoms in methoxy and acetyl groups have T values ranging between 1 and 3 a. From these results a quantitative determination of interunit linkages in lignin may be possible from car-bon-13 spectra with pulse interval times of at least 3 s.