Baroness Thatcher is resting at her London home after spending the night in hospital undergoing tests.
Baroness Thatcher told waiting reporters that she was feeling better
The 82-year-old former UK prime minister was admitted to St Thomas' Hospital in London after falling ill at a House of Lords dinner.
Her spokesman said she had felt "giddy and queasy", but tests revealed "nothing of substance".
Lady Thatcher waved and smiled at photographers as she walked to a waiting car on leaving hospital.
In 2002, Lady Thatcher had a series of minor strokes and was advised by doctors to stop making public speeches.
'Bit of rest'
A spokesman for Lady Thatcher said they thought it best to take her to hospital for tests after her "legs buckled" at the end of the function.
Her daughter, Carol, said the decision to take her mother to the nearby hospital was a wise one given her medical history.
"But it's good news today. She is doing well."
Mark Worthington, Lady Thatcher's private secretary, said she was in good form and that the tests revealed "nothing of any substance".
"She's very comfortable at home, she's sitting up in her sitting room and we've all been chatting away," Mr Worthington said as he left her Belgravia home.
He said she was not taking any phone calls.
"She's going to have a quiet day and we're going to let her get a bit of rest," he added.
Prime Minister Gordon Brown said: "I and others wish her well in a very speedy recovery".
Conservative leader David Cameron said he was "delighted and relieved" at the news that Lady Thatcher was home.
"I'm sure the entire country will join me in wishing her a full and speedy recovery," Mr Cameron said.
Baroness Thatcher met Chelsea pensioners last month
Charles Moore, former editor of the Daily Telegraph and a biographer of Lady Thatcher, said she is susceptible to heat, which can cause her to take "a turn".
"I think that's what's happened but obviously there is always some concern with someone that age."
The Tory peer's strokes have affected her short-term memory, according to friends, but she continues to fulfil a number of public engagements.
She last appeared in public three weeks ago when she opened a new infirmary for Chelsea pensioners.
In January, Lady Thatcher was presented with a lifetime achievement award by Mr Cameron at a ceremony in London.
She won praise from Prime Minister Gordon Brown during a high-profile visit to Downing Street last year. Labour's long-time foe was, he said, a "conviction politician".
It was a visit that led Tory MPs to accuse Mr Brown of hypocrisy.
Lady Thatcher lives in Belgravia, central London. Her husband, Sir Denis Thatcher, died in June 2003, aged 88.
She was prime minister for 11 years before resigning, under pressure from her party, in 1990.