In a live Web chat to mark World Book Day, Rowling — who has always insisted she'll write only seven Potter books — was asked by a fan if she intended to write books about Harry after he leaves Hogwarts, the academy for wizards.
"Probably not. But I'll never say never because every time I do, I immediately break the vow," she replied.
Rowling, whose wealth was recently estimated at $1 billion, is writing the sixth Potter book. The most recent installment is "Harry Potter and the Order of the Phoenix."
"I can't say when it will be released because that's down to my publishers," she said. "But it's going really well. I am loving writing it."
She promised the latest book would include more romance for the boy wizard, but hinted he would also face a terrible ordeal. She added that she planned to try a "completely different genre" of writing when she has finished the seventh book, but did not specify.
More than 16,000 Potter fans submitted questions during the hour-long discussion.