The one- and two-dimensional nuclear magnetic resonance spectra of X-ray-irradiated poly(methyl methacrylate) (400-MHz H-1 and 100-MHz C-13) have been obtained. The one-dimensional hydrogen spectrum and the two-dimensional H, H-COSY, HMQC, and HMBC spectra allow the assignment of 28 hydrogen and carbon NMR signals for the four polymeric degradation products plus six signals for minor stereoisomers. Methyl formate and acetaldehyde were also observed.