A tradesman allegedly bashed a 65-year-old to death in her Sydney waterfront mansion before stealing cash, a court has heard.

Concreter Tony Halloun, 35, is accused of bashing Shahnaz Qidwai to death in her mansion at 24 Dick Street, Henley, on Sydney's lower north shore on June 15, 2012.

Her body was found on a bedroom floor by one of her four adult children - 28-year-old daughter Maha, who returned home from university around 2:00pm.

In his opening address to the jury, prosecutor Giles Tabuteau said Halloun, whose company was called Totalcrete, was renovating the driveway of the home.

He said Ms Qidwai usually did office work for her husband Khalid, who had a medical practice at Croydon, but she had decided to stay home that day.

"The Qidwais were a close family," Mr Tabuteau told the NSW Supreme Court.

The prosecutor said an autopsy showed the victim died from blunt force injuries to her head, chest and ribs.

He said after bashing the woman Halloun took cash from the house.

The court heard that the day before that Halloun had demanded money from Khalid Qidwai, telling him "I will win in the end".

Mr Tabuteau told the jury they would hear evidence that Ms Qidwai had told family members she did not feel comfortable around the tradesman.

The prosecutor said Halloun had thousands of dollars worth of debts.

He said another labourer working with Halloun that day said he was sweating when he came out of the house and drove erratically afterwards.

The prosecutor said neighbours heard screaming from the house.

Halloun has pleaded not guilty.

His trial before Justice Lucy McCallum is expected to run for up to eight weeks.