The Melbourne Magistrates Court has heard a drug-addicted anaesthetist infected 56 patients with hepatitis C by contaminating syringes.

James Peters, 62, is accused of infecting the women while working at a day surgery in Croydon and is facing 168 charges.

A pre-trial hearing has heard Peters was diagnosed with the hepatitis C virus in 1997 and became hopelessly addicted to the pain medication fentanyl.

The prosecution said it was the restricted access to the drug that ironically led to him infecting patients.

It is alleged the doctor would surreptitiously use pre-filled syringes intended for patients.

The court heard he would turn his back to staff, inject himself and then use the contaminated needle to administer the pain relief.

The court also heard the Medical Practitioners Board was informed about this addiction to the pain medication.

The court was told a Department of Human Services investigation failed to find out how the doctor was linked to the cases, despite one consultant knowing of his drug addiction.