Love Story actor Ryan O'Neal has died of heart failure, according to his death certificate.
The 82-year-old suffered from cardiomyopathy – a disease of the heart muscle – and died on December 8 in a California hospital.
O'Neal suffered from heart disease for years and had survived two bouts with cancer.
A friend said: 'Ryan's lifestyle was catching up with him. He spent years partying and all those drugs weakened his heart. It's amazing he's lasted this long.”
Cardiomyopathy causes a thickening of the heart wall and causes the muscle to weaken.
Love Story actor Ryan O'Neal died of heart failure at the age of 82, his death certificate reveals
O'Neal had a 30-year relationship with Charlie's Angels star Farrah Fawcett until her death in 2009.
O'Neal was best known for his 1970s films, including Paper Moon, with his daughter Tatum, 60, who at the age of 10 became the youngest person ever to win an Oscar.
He starred with Barbra Streisand in What's Up Doc? and was featured in the 1970 tearjerker Love Story, about a wealthy student who falls in love with a working-class girl.
The actor was more known for his off-screen antics.
O'Neal starred opposite Barbra Streisand in the boxing comedy The Main Event in 1979, as well as What's Up Doc? in 1972
He had a thirty-year relationship with Charlie's Angels star Farrah Fawcett until her death in 2009.
O'Neal had three sons, Patrick, 56, Griffin, 59, and Redmond, 38 – his child with Ms Fawcett.