An 11-year-old Sydney girl is suing fast food chain KFC for just over $10 million, claiming she was poisoned at one of its restaurants.

Monika Samaan arrived at the New South Wales Supreme Court this morning in a wheelchair.

She has acquired spastic quadriplegia and a profound intellectual disability.

The court has heard that her condition was due to salmonella poisoning from a contaminated KFC product called a 'twister.'

She ordered the product from the Villawood outlet in Sydney's south west in October 2005.

The next day she was vomiting and had diarrhoea. Her parents and brother were also sick after sharing her twister.

The family's lawyer, Anthony Bartley SC, told the court that Monika Samann had been an extremely bright and active young girl before her illness.

KFC is accused of breaching its duty of care and the Trade Practices Act.

The court heard that a company review conducted last week gave the Villawood outlet a performance ranking of 41 per cent.

That is regarded as a breakdown standard.

The hearing continues.