NSW Health has issued a warning to customers of Sokyo restaurant at The Star casino complex in Sydney that a staff member has been diagnosed with hepatitis A.

Dr Vicky Sheppeard, the director of communicable diseases at NSW Health, said patrons may have been exposed to hepatitis A if they dined at the Japanese restaurant during the evening of September 20-24, 26, 27 and 29, October 2 and October 4-8.

A staff member at Sokyo restaurant has been diagnosed with hepatitis A.

She also said patrons should visit their GP if concerned.

"There is a safe and effective hepatitis A vaccine available through GPs for those who are worried," Dr Sheppeard said. "But the hepatitis A vaccination is not considered necessary on the basis of this low-risk exposure."