Former Cabinet Minister Chua Sian Chin, a member of Singapore's first generation of leaders, died on Wednesday of heart failure.
He was 81. Mr Chua had suffered from dementia since the late 1990s.
First elected in 1968, he was immediately made health minister, making him the youngest Cabinet minister then at 34.
He went on to spend 27 years in politics, and also held ministerial portfolios in Education and Home Affairs.
As Home Affairs Minister, he was associated with several landmark changes, including the crackdown on secret society activities and the drug problem. He was also involved in the setting up of grassroots organisations.
One of his first projects then was the "Keep Singapore Clean" campaign, which he launched in 1968. At his retirement in 1991, he told The Straits Times that it was his most important contribution to Singapore.
When he stepped down, he was one of only two members of the Old Guard, apart from then-Senior Minister Lee Kuan Yew, still in politics at that time.
Last year, his son, Mr Chua Eng Leong, 43, was appointed by the People's Action Party as its branch chairman for the Eunos ward in Aljunied GRC.