A double-resonance surface-coil NMR probe is described for performance of high-field (8.5 T) proton decoupled carbon-13 experiments with tissue in vivo. The probe may be accommodated in standard, 89 mm i.d. clear bore, commercial spectrometers and is suitable for studies utilizing small laboratory animals such as mice, hamsters, and rats. A coaxial coil design is employed (10 mm diameter 13C coil, 20 mm diameter 1H coil) which provides ca. 40 dB attenuation between the 13C observe and 1H decouple channels. The inherent efficiency of the surface-coil configuration provides a sensitivity comparable to a commercial probe of the same nominal dimension (10 mm Helmholtz coil) and assures adequate decoupling in conductive samples with ca. 3-5 W power. In the absence of 13C isotopic enrichment, NMR spectra of rat leg, liver, and brain in vivo provide signalto-noise sufficient for 10 min time resolution. Administration of 100 mg of 90% 13C-labeled glucose into a peripheral vein of a ca. 300 g rat resulted in a liver glucose resonance which could be monitored with good signal-to-noise and 3 min time resolution.