From the analysis of defense regulations, interviews with officials, and tests of billing and collection transactions involving the Air Force system for recovering costs, it was found that the Air Force has not recovered from foreign governments millions of dollars for costs incurred in training foreign students. For 1975, at least $5.7 million in cost were incurred because the Air Force did not charge foreign governments at current tutiton rates, used erroneous tuition rates in billing foreign governments, and did not include aircraft depreciation costs in tuition rates. Further, substantial additional costs will not be recovered for courses conducted in 1976 unless prompt corrective action is taken to ensure that current tuition rates are used in billing foreign governments. Moreover, the Air Force Secretary should attempt to recover amounts not previously charged because outdated and incorrect rates were used and require a periodic review of the biling system for services provided to foreign nations. Finally, foreign countries should also be billed for aircraft depreciation costs incurred in providing flight training to foreign military students.