Fifty-two Notorious Mongrel Mob members, affiliates and extended family took part in research published yesterday in Royal Society Open Science.
The study assessed hepatitis prevalence, knowledge and liver health risk factors and included about 20 Dunedin-based participants.
Associate Professor Michael Schultz, head of the Department of Medicine, said fifth-year medical student Jordan Tewhaiti-Smith, who came from a gang family, ''basically opened the door'' for the research to be done.
Among the challenges posed by working with the gang members was that they and the researchers had to ''meet on neutral ground''.
The Salvation Army allowed them to use their premises, Associate Prof Schultz said.
The researchers spoke to the elders, who would ring and say there were carloads of people arriving to participate.
''It was a lot of ad hoc recruitment.''
Mr Tewhaiti-Smith, who hoped to go into either surgery or oncology once he graduated, hoped to take part in similar studies in the future.
It was a ''really good example'' of engaging with marginalised groups, he said.
The biggest challenges were logistical, which was why a fairly small number of people had taken part.
Members of the gang were considered to be at a higher risk for hepatitisC due to common intravenous drug use, uncertified tattooing and a high incarceration rate.
Associate Prof Schultz said the ''marginal'' knowledge study participants had about viral hepatitis was concerning, and the study demonstrated the need for educational screening programmes to aid in detection, prevention and treatment.
However, the research subjects were ''very nice and co-operative and really interested'', Associate Prof Schultz said.
Researchers identified several areas of concern, including three times higher rate of liver inflammation and damage compared to the general population.
One-fifth of study participants had significant to severe levels of liver fibrosis and cirrhosis, and participants reported ''exceptionally high'' levels of alcohol consumption.