La saison 1 de Les Professionnels a été diffusée à partir du 30 décembre 1977.

The first series set the standard for five successful years, milking the dramatic potential of a rich gamut of scenarios, from international espionage to racism and religious evangelism; Bodie and Doyle usually being called upon to protect a controversial figure from the assassin's bullet. Shaw would later dismiss The Professionals for its stereotypical violence and for a long time refused to allow reruns. In fact, as cult television goes, it has weathered well. Many of its themes are as relevant today as they were then. The constantly elliptical script ("I want you to see that he's… well taken care of") is tremendous fun. And despite the macho drive, the whole thing has a camp archness which betrays its Avengers pedigree. Great for a nostalgic wallow.

La saison 2 de Les Professionnels a été diffusée à partir du 7 octobre 1978.

In series two, Doyle is assigned to test a new laser-beam rifle, Bodie's girlfriend is critically injured in a terrorist bombing, and the team go up against a rogue agent.

La saison 3 de Les Professionnels a été diffusée à partir du 27 octobre 1979.

In series three, CI5 is targeted by a series of bombings and assassination attempts, the team investigates the murder of a defector, and Bodie and Doyle begin to suspect that their boss is selling weapons to the East Germans.

La saison 4 de Les Professionnels a été diffusée à partir du 7 septembre 1980.

In series four, the CI5 protect the daughter of a visiting South American president after his son is assassinated, and the team uncover a silver bullion smuggling operation being controlled from behind the Iron Curtain.

La saison 5 de Les Professionnels a été diffusée à partir du 7 novembre 1982.

More running around action from the popular 1970s action series. In 'Hunter/Hunted', a hi-tech rifle is stolen from CI5, and the boys have to track it down before its deadly force can be unleashed. In 'Stakeout', a CI5 agent is murdered before he can pass on details of a major crime. Bodie and Doyle soon discover a case of Plutonium poisoning.