NSW Health Minister Jillian Skinner has defended her decision to spend nearly $85,000 on a taxpayer-funded trade mission to China while the chemotherapy dosage scandal was spreading in Sydney.

Opposition Leader Luke Foley has accused the minister of making the 11-day trip in April just after she learned that patients at St George and Sutherland hospitals had been incorrectly treated for cancer in a similar fashion to others at St Vincent's hospital.

"The chemotherapy under-dosing scandal was unfolding before her very eyes and yet Ms Skinner's reaction was to pick up the phone to the government travel agent," he said on Tuesday.

"Premier (Mike) Baird needs to find a new health minister - one who puts patients ahead of international travel."

But Ms Skinner said she was not made aware of allegations that haematologist Dr Kiran Phadke may have under-dosed several cancer patients at Sutherland and St George hospitals until after she returned from the trip on April 21.

She defended her decision to go on the "health-focused trade mission", saying it led to phenomenal investment outcomes for taxpayers.

"As a direct result of the trip, we signed several memorandums of understanding," she said.

"One affirmed the commitment of NSW and Shandong province to collaborate in health fields of shared interest including staff exchanges, medical research, new technologies, clinical trials and partnerships with universities."

The minister also defended her spending record, arguing that the former Labor MP Joe Tripodi spent $290,000 alone on travel in 2009.

"Last year, the NSW government spent $800,000 overseas. Can you believe that?" she told parliament.

"The last year of your (Labor's) government was $1.5 million. We get something for our investment."

Ms Skinner was accompanied by her chief-of-staff Dr Kerry Chant and a delegation of 26 health officials and industry experts on the trip, which included meetings in Shanghai, Beijing, Jinan and Hong Kong.

The health minister has come under pressure to resign in recent weeks over her handling of the under-dosing scandal as well as a mix-up that led to newborn babies being given nitrous oxide instead of oxygen at Bankstown-Lidcombe hospital.