The Drug Foundation says doctors are fearful of medicinal cannabis.
Executive director Ross Bell said the science around cannabis was getting stronger and he did not think medical professionals who oppose its use were up to date.
Mr Bell said their scepticism was driven by an underlying fear of the drug because it had been illegal for so long.
He said medical professionals were generally quite conservative and did not want to be seen as soft on drugs.
Mr Bell also said medical specialists were reluctant to put in applications supporting medicinal cannabis to the Health Minister.
The Medical Association's deputy chair, Dr Kate Baddock, said GPs were educated in all areas and the idea that doctors were fearful of cannabis was nonsense.
She said more clinical trials needed to be done in the field as there was not enough evidence of its benefits.