We have measured the amount of vibrational energy transferred to translation inV‐Vcollisions between SF6and helium or argon. We used precise mass‐spectrometric measurement of the change in SF6density in a flow of He or Ar and SF6through a focused cw CO2laser beam under conditions where the number of collisions in the beam was much less than the collision number forV‐Tdeactivation. We have determined the ratio of energy lost &Dgr;? to the number of collisions forV‐VrelaxationZVVto beZ−1VV&Dgr;? =13±6 cm−1/collision for helium and 4±2 cm−1/collision for argon. These values are independent of temperature over the range 150–300 K.