CHICAGO - Oprah Winfrey has discovered she has a half-sister - a Milwaukee woman who was given up for adoption by Winfrey's mother nearly 50 years ago, when the talk show host was 8 years old.

An emotional Winfrey introduced her newly found sibling to viewers Monday and explained the woman's persistent quest to find her birth mother.

"This, my friends, is the miracle of all miracles," Winfrey said before bringing out the 48-year-old woman, who throughout the program was identified only as Patricia, with no mention of her occupation or any other details.

After years of searching for blood relatives, the woman met Winfrey on Thanksgiving Day of last year.

When Patricia was born in Milwaukee in 1963, the young Winfrey was living with her father and did not even know her mother was pregnant, she said.

Patricia, who Winfrey said bounced from foster home to foster home until she was adopted at age 7, had given up after previous searches for her mother. But she decided to resume looking several years ago at the insistence of her grown children.

The effort seemed to hit a dead end when a woman from the Wisconsin adoption agency called to respond to her inquiries.

"She was telling me that my birth mother had called her back, and she had made the decision at that particular time that she did not want to see me," Patricia said.

Coincidentally, on the local news that day was a story about Winfrey's mother, Vernita Lee, who revealed details about two of her children who had since died. Those details, Patricia said, matched information she had seen in papers about her own adoption.

Winfrey's mother also said that one of the deceased children had been named Patricia.

"The hairs on the back of my neck stood up," Patricia said. "Because I knew one of my siblings and I shared the same name."

Later, she found more matching details, including the fact that Winfrey was born in 1954, the same year as the woman Patricia knew was her surviving sibling.

Patricia found the daughter of Winfrey's dead sister in Milwaukee, and they took a DNA test that confirmed their relationship.

Lee, who recently suffered a minor stroke, said she never told Winfrey about her half-sister, "because I thought it was a terrible thing for me to do, that I had done, gave up my daughter when she was born."

Winfrey said documents from the girl's birth reveal that Lee gave up the baby for adoption because she did not think she could get off welfare if she kept the child.

"I made the decision to give her up because I wasn't able to take care of her," Lee said during a recorded interview that aired Monday. "So when I left the hospital, I told the nurse I wasn't going to keep the baby."

Winfrey said she was particularly stunned by the news because of the way it came out.

She said Patricia had known since 2007 that the two were related, but never attempted to profit off her discovery or contact the press, even as she tried unsuccessfully to contact Winfrey, her mother or others in Winfrey's family.

"She never once thought to sell the story," Winfrey said, recalling how she felt betrayed by others who have sought to take advantage of their relationship with one of the largest figures in the entertainment world and one of the wealthiest women in the United States.

Winfrey, for example, recalled how her other sister revealed to the press years ago that Winfrey had had a baby when she was a teenager. The baby, Winfrey has said, died shortly after birth. And she talked about putting her sister in rehab twice for drug addiction, but that her sister ultimately died.

Patricia said she didn't consider revealing that she and Winfrey were half-sisters to anyone but Winfrey, explaining that she did not want to hurt Winfrey.

"Family business should be handled by family," Patricia said. "It couldn't be handled by anyone else. That's not fair. It wouldn't be fair to you."

Winfrey said she was heartened by learning that she had a half-sister, saying it "feels like closure" for the sister who died.

"It feels to me like you are Pat on her very best day," Winfrey told the woman. "You are what she wanted to be without the drugs."