  We present observations of CO overtone bandhead emission toward four massive
Young Stellar Objects (spectral type O6--B5). The high signal-to-noise ratio
K-band spectra were obtained with VLT-ISAAC at a resolution of 30 km/s,
sufficient to resolve the bandheads, but not the individual J-lines. We are
able to explain the shape of the lines by assuming a simple isothermal
keplerian disk model seen at different inclinations. The gas temperature ranges
from 1500 to 4500 K and the CO column density is between 0.1 and 4 10^21 cm^-2.
The emission probably arises within the first few astronomical units of the
disk, consistent with the high gas temperature. Our results indicate that
molecules can survive close to a hot star and suggest that dense (n_H > 10^10
cm^-3) inner disks may be relatively common at an advanced stage of high-mass
star formation.
