Series star KaDee Strickland (Charlotte King) recently dismissed rumours that the programme is to be axed, following a move to a new Tuesday night slot.
"I'm never going to say that I absolutely know it's coming back until the network tells me that it's coming back but I'm hopeful," show creator Rhimes told The Hollywood Reporter.
"I feel like we've done our job for the network for a very long time and we're continuing to do it. It's really great to know that we have done better in that [Tuesday] time slot and held more audience than has ever been held before... and I hope the network recognizes that."
Rhimes added that she considers May 15's fifth season ender "a season finale, not a series finale".
"We did leave some questions unanswered and I think that was the only way for me to do it," she explained. "I refused to go with the idea that this was the end of the show."
It was recently reported that Private Practice could return for a final, shorter season of 13 episodes, with ABC having been impressed by the programme's performance on Tuesdays.
The series airs Tuesdays at 10/9c on ABC.