Six inmates from a prison in Wiltshire have qualified as health trainers so they can offer information and support to fellow prisoners.
The prison has been working with NHS Wiltshire to develop the service and hopes the group can help to improve mental and physical health in the jail.
One of the men learned sign language in order to be the voice of another member of the group who is deaf.
The team can offer advice on lifestyle changes and drugs and alcohol services.
Director of public health for NHS Wiltshire, Maggie Rae, said: "Mental and physical health is known to be one of the key influences on reoffending.
"By providing prisoners with the knowledge, skills and support needed to lead healthier lifestyles, health trainers can both encourage other prisoners to improve their health whilst helping to reduce reoffending."
Paul Wiltshire, deputy governor at HMP Erlestoke said: "Training is currently being planned for a second cohort of health trainers since many of the present group will move on from Erlestoke by the beginning of 2010."