So it will come as good news that the show's US parent studio Warner Bros and its producer Chuck Lorre have signed a deal which will keep the show in production for three more seasons.

The deal extends the series through to what the US market calls "the 2016-2017 television season". In a nutshell, it ensures that an eighth, ninth and tenth season of the show will be produced.

Signing a deal for a three season renewal, particularly so late in a show's life, is a rarity. Most programs are given season by season renewals by US studios once they have reached their sixth year.

The series, about four nerds working in various fields of scientific academa, stars Johnny Galecki as Leonard Hofstadter, Jim Parsons as Sheldon Cooper, Simon Helberg as Howard Wolowitz and Kunal Nayyar as Raj Koothrappali.

Kaley Cuoco plays Penny, the girl who lives next door to the apartment shared by Galecki and Parsons' characters. In later seasons Melissa Rauch and Mayim Bialik joined the cast as girlfriends for Helberg and Parsons' characters.

In the US, it is an unqualified hit in a television market peppered with unqualified hits. In Australia, however, The Big Bang Theory's place in the ratings mosaic is somewhat more unique.

For the Nine Network it has been a saving grace, particularly through several lean years, several less lean years ago, when Nine's schedule was not so strong, and the hits were fewer and further between.

But it has also been Nine's bane - at least in perception terms - as the network milked it to survive those lean years, programming it into, what seemed at times, any slot which needed a programming band aid.

At times, Nine screened it as many as 15 times in a single week, including first run episodes and many, many repeats.

The Warner Bros-Chuck Lorre seal would seem to secure Nine an unending supply of repeats, but there is still some fine print to be worked through.

The deal ensures the producers will deliver the show to the studio. Still to be determined are the long term contracts of the show's cast, which require Warner Bros and the show's US network CBS to negotiate with the actors' agents.

Bialik and Rauch, who joined the show midway through its life, have already been signed to longer term deals. The show's five original cast - Galecki, Parsons, Helberg, Nayyar and Cuoco - are on contracts which expire at the end of the show's current, seventh, US season.

Those negotiations could send their salaries - currently in the $US300,000 to $US400,000 range - sky-rocketing.

The Big Bang Theory airs in Australia at 8.40pm on Tuesdays on the Nine Network.