Marcel Dassault gave the go-ahead for production of an eight or ten seat executive jet or military liaison aircraft named the Dassault-Breguet Myst-re 20 in December, 1961. The Myst-re 20 was a low-wing monoplane with two rear-mounted Pratt & Whitney JT12A-8 engines.
The prototype, registered F-WLKB, first flew on May 4th, 1963 at Bordeaux-Merignac. Under the influence of Pan American the aircraft was re-engined with two General Electric CF700 engines and some dimensions were increased. Pan American signed a contract to distribute the Myst-re 20 in the western hemisphere and ordered 40 aircraft with options for another 120. The re-engined aircraft first flew on July 10th, 1964. The first production aircraft flew on January 1st, 1965 and both French and American certification were awarded in June, 1965.
On June 10th, 1965, Jacqueline Auriol set the women's world record speed in the first Myst-re 20 prototype, F-WLKB, with an average speed of 859 kilometers per hour over 1000 km. This prototype was used in the 1966 comedy How to Steal a Million, starring Audrey Hepburn and Peter O'Toole. The Deliveries began to the Pan American outfitting facility at Burbank Airport, California. In 1967 the Pan American Business Jets Division, a business unit of Pan American World Airways, increased their firm orders to 160 aircraft. Some Falcon 20s powered by General Electric CF700 engines were reengined with Garrett TFE731 engines under AMD-BA Service Bulletin No. 731. These aircraft were redesignated with a '-5' after the model number. Volpar, Inc. worked on a program to reengine Falcon 20s with the Pratt & Whitney Canada PW305 engines, but the program was abandoned before a FAA STC was awarded.