Inkatha Freedom Party MP Mario Oriani-Ambrosini died on Saturday after battling cancer, his family said.
"It is with deep sadness that we, the family of Dr Mario Oriani-Ambrosini, advise of his passing in the early hours of this morning, after a long and courageous battle with terminal lung cancer," they said in a statement.
"We wish to thank everyone who offered such tremendous support over the past 19 months."
The family said the love and warmth shown to Oriani-Ambrosini and to them from friends was appreciated.
Oriani-Ambrosini announced last year that he had been diagnosed with stage four lung cancer.
At the time, he said his doctors did not expect him to see Christmas 2013.
Oriani-Ambrosini said he had rejected chemotherapy as a treatment option, as it would extend his life expectancy by only a few months and would cause severe side-effects. He had opted to pursue treatment based on "different science".
In February this year, he tabled legislation to decriminalise the medical use of dagga.
Oriani-Ambrosini, who returned to the National Assembly earlier this year after months of absence, made an impassioned plea to President Jacob Zuma and his government to decriminalise "medical marijuana".
Source : Sapa