Prescription drugs should be monitored in real time to stop overdose tragedies, Heath Ledger's father says.

Heath Ledger's father hopes prescription drug monitoring systems will help prevent more tragedies such as his son's death.

Kim Ledger started Scriptwise, a non-profit foundation set up to educate people about the dangers of abusing prescription drugs.

He said doctors needed to know if people were shopping around for prescription pills.

"People with higher profiles probably get questioned less, whatever you want you can have," Mr Ledger told ABC 24 on Thursday.

"But it is as simple as right now there is not system to catch it. So you can literally go from one doctor to the next in Australia and build up an armoury of pills."

Mr Ledger said real-time monitoring systems would keep track of people who were collecting dangerous levels of prescription drugs.

"When they first put the system together in New York, I think it was the first day they found 200 doctor shoppers," he said.

Heath died of an overdose in 2008, leaving a daughter Matilda with actress Michelle Williams.

Mr Ledger said Ms Williams did a great job making sure her daughter knew who her father was.

"She's a good mum, and she spends a lot of one-on-one time with Matilda, and she really keeps Heath alive in her life, all the time," he said.

"Not just photos, but she talks to Matilda all the time about her dad.

"Of course when we see Matilda she's full of questions as well, always wanting to know who's connected to who, where her place in the family is and little questions about her dad.

"I guess that'll just get a little stronger as she grows and becomes a little more curious, which is good."