Up to 30 per cent of Australians with atrial fibrillation, an irregular heartbeat that increases their risk of having a stroke, are undiagnosed.

Hundreds of thousands of Australians may be living with an undetected killer that is putting them at serious risk of stroke, experts warn.

Around 460,000 Aussies have atrial fibrillation, an irregular heartbeat which can be fatal if left untreated.

Atrial fibrillation (AF) can often be asymptomatic and yet can present for the first time with a severe disabling stroke, according to the Asia Pacific Heart Rhythm Society (APHRS).

Up to 30 per cent of Australians with AF are undiagnosed, putting them at serious risk of stroke, heart disease and even death.

Stroke Foundation Chief Executive Officer Sharon McGowan says there needs to be more awareness of AF in the community.

"More than 14,000 Australians will have a stroke caused by atrial fibrillation this year, which is why it is crucial we do more to detect and manage this dangerous condition," Ms McGowan said.

One in six people will have a stroke in their lifetime. Currently in Australia it's estimated there are 1000 strokes every week, or one stroke every 10 minutes.

During the world's first-ever Atrial Fibrillation Awareness Week (4-10 July), the Stroke Foundation in partnership with hearts4heart will conduct free heart screenings at hospitals across the country to help detect AF and raise awareness about this potentially deadly condition.

Ms McGowan says a quick 30 second screening could mean the difference between life and death.

"Stroke does not discriminate, it impacts men and women at any age," she said.