Evidence for accretion disks around massive stars are presented, based on high spectral resolution (lambda/dlambda~50 000) of the CO 2.3mu 2-0 vibrational-rotational band head. Keplerian signatures indicates that massive stars form by accretion disks, at least up to ~20 Msun. To date, no evidence for disks where found for spectral types earlier than late O-type, suggesting that the timescale for dissipating their disks is much faster than that of the less massive OB stars or that the most massive stars do not form with accretion disks.