Six Nigerian men and one Zambian have appeared in court in South Africa on charges relating to impersonating doctors and endangering people's lives.
They were also accused of corruption, fraud and indecent assault.
The men are alleged to have been running at least six private practices. The suspects did not enter a plea.
CSI Africa, a private investigation firm, says the medical profession is one of the most targeted by fraudsters in South Africa.
According to its research, fake qualifications run at between 15% and 18% across various professions in the country.
The men appeared in the Middleburg Magistrates court in Mpumalanga province along with two qualified Nigerian doctors who are alleged to have allowed their medical numbers to be used to register more practices.
The case was postponed until 23 February.
McIntosh Polela, a spokesman for South Africa's special Hawks police investigation unit, said the suspects would remain in police custody until then.
The Hawks were investigating reports that the six men were linked to a syndicate operating across South Africa, he said.
South Africa's Board of Health Care Funders (BHCF) has said it is concerned that thousands of people may have been misdiagnosed by the suspects.
The medical lobby group said it had launched a separate investigation into reports that up to 17 other people have been posing as doctors have been treating patients in government and private hospitals.
Last week, a man who claimed to be a doctor was arrested after the woman he performed a caesarean section on died in the Eastern Cape province.