Belgian newspaper Het Nieuwsblad reported that the 25-year-old Henin would make the announcement some time tonight. "For a while now the Belgium's No.1 in the world has been having problems with fatigue and getting into her game," the paper said. This year she lost to Serena Williams, Maria Sharapova and Italy's Francesca Schiavone. Last week she was ousted from the Berlin Open in the third round and this week she pulled out of the Italian Open, Fox sports reported. A four-time French Open winner, Henin has captured seven Grand Slam titles and has 41 overall for her career.
She first rose to No. 1 on October 20, 2003, and this week marks her 61st consecutive week at the top of the rankings and 117th overall.
The winner of the last three championships at Roland Garros, Henin has two titles this year - in Sydney and Antwerp. She was ousted by Russian Maria Sharapova in the quarterfinals at the Australian Open, the first Grand Slam event of 2008.
Henin would be the second Belgian women's tennis star to retire in as many years after Kim Clijsters called it quits in 2007.
Despite a troubled personal life - her mother died in 1995, her father did not speak to her for eight years and she divorced in 2007 - Henin won an Olympic gold medal, and took the title of every major tournament except Wimbledon.
Her top year was 2007 when she earned more than five million dollars, winning 63 of her 67 matches in 10 tournaments, including two Grand Slams.