- German Air Force – 46 T-38A in 1968, now upgraded to T-38C. All aircraft are stationed at Sheppard AFB, Texas and are painted in US markings.
- Portuguese Air Force – 12 aircraft in 1977. Initially operated by 201 Sqn. “Falcões“ (Falcons) at Air Base No. 5, in 1980 they were transferred to 103 Sqn. “Caracóis“ (Snails) being stationed in Air Base No. 11. They were retired in 1993 replaced by Dassault/Dornier Alpha Jet
- Republic of Korea Air Force – thirty T-38A from the US in April 1999. All units were returned to the US by 2009 after near completion of production of T-50 Golden Eagle supersonic trainer.
- United States Air Force – 500 T-38 trainers in service as of September 2018