Home And Away's Alf Stewart and Marilyn Chambers are set to face some serious set-backs in future storylines.

Alf - played by Ray Meagher - ignores his heart problems at his peril, preferring to get caught up in daughter Roo's relationship with Harvey and Romeo's marriage breakdown.

"His own personal barometer is telling him that something's amiss, but he won't address that. He just pulls his boots on and gets on with it - until it knocks him on his backside," the actor told Australian magazine TV Week.

Things come to a head when he ends up on the floor.

"Alf does have a history of heart complaints - is this a return of his previous problems? If anyone ends up on the deck in that much pain, you'd have to be concerned for their health, so it's very serious," he continued.

Meanwhile, his long-time friend Marilyn (Emily Symons) gets a shock after she is attacked and mugged on the beach, and despite his own health issues, Alf insists on getting involved.

"He's worried on two fronts: one, that Marilyn was mugged and anything could have happened; and, two, that this sort of behaviour is going on in the Bay and a person can't walk down the street without this sort of rot," he added.