The Launceston family are credited with saving more than 1050 lives, with more than 350 blood donations between them.

Mrs Garwood made her first blood donation in 1975 and earlier this year reached her 200 milestone.

Describing it as a simple thing that could make a big difference, she said while she had always been in good health, there were many who weren't.

"I figured if I could help others in some way, it was worth it," she said. "It is a bit like organ donation - if you find yourself in the position of needing it yourself, you should be willing to donate."

National Blood Donor Week, held from June 9 to 15, celebrates the 470,000 "legendary" donors who together give 1.4 million donations of blood, saving countless lives each year.

However, almost half of all first-time blood donors give once and don't come back. Blood Service data shows of the 91,000 Australians who gave blood for the first time in the past 12 months, 43 per cent didn't return to make a second donation.

For Brad, who recently reached his 100 donor milestone, watching his mother inspired him to follow in her footsteps.

"I can remember as a kid going into the Launceston centre with mum and getting a lollipop," he said.

"Once I was of the age where I could start donating, it was a no-brainer. It's just one of those things that if you do it enough times, it becomes a habit and you don't think about it. We all donate and then go around to mum's for a family dinner. So it is a really special thing."

Blood Service spokeswoman Ann Harvey said "donor legends" like the Garwoods were crucial to contributing about one quarter of the nation's blood supplies, however more people were needed.

"These amazing donors can't do it alone," she said.

"Australia needs a new blood donor every five minutes. It takes just an hour of your time to donate blood and every donation can help save up to three lives."