The new drug has been proven to help patients
The new drug, Enbrel, has been on the market since last year but so far only 30 Welsh patients are able to use it.
Enbrel has been acclaimed as a highly effective treatment for severe rheumatoid arthritis.
It allows many patients crippled by the disease to resume a normal life unrestricted by a lack of mobility or pain.
But the treatment is expensive with a year's supply costing around £8,000.
Rheumatologists have estimated that around 500 patients in Wales would benefit from the new drug but some health authorities are reluctant to take on the cost.
According to Professor Brian Williams from the University Hospital in Cardiff there are widespread variations.
He claims that he is able to prescribe the drug to patients from west Wales or Swansea, but not to patients from south Wales.
"There is a moral issue about availability uniformity within the health service of effective therapy," he said.
"In south Wales people do very badly if you live in certain areas you will be denied access to the drug simply in the basis of where you live, irrespective of you need and that cannot be defended."
Dramatic effects
Research has suggested that around 600,000 people in the UK have rheumatoid arthritis.
Enbrel, has been proven to help combat the symptoms of the disease which is caused by an inflammation in the lining of the joint.
It has been found to dramatically reduce pain, stiffness and joint swelling.
"It is also important the effects the drug has on slowing the process of joint damage is significant therefore the need for surgery may well be prevented in the future," professor Williams added.