His experience helping his brother Christiaan perform the world's first heart transplant in 1967 helped him realise there was a need to help people deal with the financial costs of surviving a major illness.
He invented critical illness insurance in 1983 after noting that many of his patients saw their lifestyles worsen due to the cost of medical care.
In later life he championed the need for quality long-term care provision which he called ‘frail care', after he was diagnosed with prostate cancer.
After semi-retiring he acted as a technical consultant for Scottish Widows.
Johnny Timpson, Scottish Widows financial protection specialist and planning manager, said:
"It is with much sadness to report that Dr Marius Barnard passed away peacefully this morning with his family around him.
"Our thoughts are with his wife Inez and family.
"I was able to discuss the Seven Families initiative with Marius and he was very taken with the collaborative approach that our industry is taking in engaging consumers and gave us his support.
"His final words to me were "Johnny, my race is run".
"Friends, he has passed the baton to us, let's make sure that we carry it forward."
Peter Le Beau, managing director at Le Beau Visage and Seven Families spokesperson, added:
"He was a great man; I was privileged to have met him.
"He did great things for South African society and for the industry - he was very involved in the struggle against apartheid and he was very passionate about critical illness insurance.
"He spent the last part of his life trying to get people to take protection seriously.
"He was a transparently decent and honest man. He will be missed."
