End groups in anionically polymerized standard poly(methyl methacrylate)s (PMMAs) in the range of number average molecular weight (M-n) = 2.0 x 10(4) to 1.3 x 10(6) with narrow molecular weight distribution were determined by pyrolysis-gas chromatography (Py-GC). The characteristic fragments reflecting the end groups on the pyrogram of the PMMAs were identified by comparison with those of a radically polymerized PMMA together with the mass spectra of the characteristic peaks on the resulting pyrograms taken by a gas chromatograph-mass spectrometer (GC-MS) system. Concentrations of the end groups determined from their relative peak intensities were interpreted in terms of M-n and then compared with their reference values from the manufactures and those estimated by H-1-NMR. By this method, direct determination of the end groups was possible even for PMMA with M-n = 10(6) without using any standard polymer samples.