Former President Nelson Mandela began radiation therapy for prostate cancer, his spokeswoman said. His cancer is not considered life-threatening.
The radiation regime will require the 83-year-old to undergo treatment for about 10 minutes every day for seven weeks.
The cancer was found three to four years before it would have started causing trouble, said Mandela's urologist, Dr. Louis Gecelter.
"This isn't going to impact on his life expectancy," he said. "He's going to live until one hundred and plenty years."