Radial velocities of three Of stars - HD 148937, HD 151804, and HD 152408

Extensive coude dispersion coverage of three extreme Of stars has been obtained. There is no evidence for binary motion from the radial velocities, and it is estimated that any short-period system with a velocity amplitude larger than about 20 km/s would have been detected. Velocity gradients, indicative of line formation in an outwardly moving envelope, are found for all three stars. Even absorption lines formed in the stellar atmosphere are moving outward with a velocity of a few tens of kilometers per sec. No absorption or emission lines of these Of stars give exactly the velocity of the star itself.