The show's star Rachel Griffiths, who plays Sarah, sparked speculation about the programme's future when she hinted that she may be "unemployed" soon.
According to TV Tonight, Griffiths made the comment while at the Logie Awards in Australia.
She joked: "I'm soon to be unemployed, so I checked in with [benefits centre] Centrelink... and said, 'Looks like I'm out of a job and wanna sign up'."
However, a spokesperson for ABC told TV Line that "no decision has been made" on the future of Brothers & Sisters.
The show's executive producer David Marshall Grant said last year that he is "living with the hope" that the series will be renewed and admitted that he is not planning the end of the programme.
However, before the current season began some cast members confessed that they are expecting the show to end. Meanwhile, ABC renewed a number of its series in January, but the list did not include Brothers & Sisters.
The fifth season continues on Sundays at 10/9c on ABC in the US and on Thursdays at 10pm on More4 in the UK.