Former president Mr Idi Ami Dada is dead. Amin, 78, passed away at exactly 7 a.m. Ugandan time on Saturday.
Sources said that Amin's latest wife, whom he married a few months ago, was at his bedside when he died.
Her name was not disclosed.
Amin's family members in Kampala declined to comment on the death of the former leader.
They said one of his sons, Mr Jaffer Amin working with DHL courier company, is the only one authorised to talk about his father's death.
Amin had been in a coma at King Faisal Specialist Hospital in the Red Sea port city of Jeddah since July 18.
He was suffering from hypertension, fatigue, kidney failure and high blood pressure caused by his being overweight.
Family sources said last month that Amin was weighing 220 kgs. However, doctors in Uganda disputed the figure and said it was too high.
The former leader's life has been hanging on a haemo-dialysis machine, which acts as an external kidney.
The Monitor newspaper reported on Monday that the Amin family was looking for a kidney donor to save his life.
Two prospective donors had earlier been rejected after their bodies were found to be incompatible with that of the former leader.
Amin has lived in exile in Saudi Arabia for more than 20 years.
He toppled former president Mr Apollo Milton Obote in a coup on January 25 1971. He ruled until April 11, 1979 when he was overthrown by a combined force of Ugandan exiles and the Tanzanian army.
Obote regained power after the disputed elections in December 1980, only to be overthrown again by the military in July 1985.
He has since lived in exile in Zambia.
When contacted yesterday, Obote declined to comment on Amin's death. "No comment," he told Sunday Monitor by phone from Zambia.
Obote had earlier told the press that he wanted Amin to live longer so that he could answer for the "sins he committed".
Another former president, Mr Godfrey Lukongwa Binaisa, said he was sorry for Amin's family and the country at large for having lost an ex-president.
"Beyond that I have nothing to say but would be happy if the president allowed the body to be brought back," he said.
Amin is blamed for the death of about 500,000 people during his 8-year regime. After his overthrow, Amin flew to Libya and later to Iraq before settling in Saudi Arabia.
Amin has lived a quiet life in the desert kingdom with his son, Mr Mwanga Amin, 31, on a monthly stipend of $1500 provided by his hosts.
When his condition deteriorated, a few months ago, his other son, Mr Wasswa Amin, flew from the US to join him.
His wife, Ms Madina Amin, also flew to Saudi Arabia on July 23 to attend to him. She was joined by another son Hussein Amin.
Amin is survived by four wives and 45 children. The wives are Madina, Ms Sarah Amin, Ms Norah Amin and the newly wed who was at his bedside.
Amin's fifth wife, Ms Kay Amin died under mysterious circumstances in the mid 70s and her body was dismembered.
Sarah operates a restaurant in East London. Norah first fled to DR Congo in 1979 but her current whereabouts are unknown.
Mr Moses Amin, who the British press once alleged had been killed and eaten by his father, lives in France.
Kato is in the US while Wasswa Amin, who was in Saudi Arabia when his father died, converted from Islam to Christianity.
Mr Ali Amin and Ms Maimuna Amin are in Uganda.
Most of Amin's children are in France.