Injectable "medical" grade heroin should be offered under supervision to the most hardened addicts, say UK researchers.
A trial in 127 addicts who had persistently failed to quit the drug showed a significant drop in use of "street" heroin after six months.
Writing in The Lancet, the researchers said the "robust evidence" supports wider provision of heroin treatment.
A spokesman for the government said it would consider the findings.
Around 5-10% of heroin addicts fail to quit despite use of conventional treatments, such as methadone.
Those who took part in the trial had been using the drug for an average of 17 years and had been in treatment for 10 years.
When they took part in the programme they were on methadone treatment but were still taking street heroin on a regular basis.
The researchers - working at clinics in south London, Brighton and Darlington - found that those offered injectable heroin under the supervision of a nurse were significantly more likely to cut down their use of street heroin than those receiving oral or injectable methadone.
Improvements were seen within six weeks of starting the programme, they reported.
In further analysis yet to be published, it was noted that the benefits remained after two years and some patients were able to stop use of the drug altogether.
Study leader, Professor John Strang, from the National Addiction Centre at King's College London, said the supervised heroin programme enables patients to start thinking about employment, re-engaging with their families and taking responsibility for their lives.
"This is a treatment for a severe group of heroin addicts that ordinary treatments have failed with and the question we're answering is 'are these patients untreatable?'."
"The very good news is that you can get these people on a constructive trajectory."
He said the latest study plus a series of other trials now provide clear evidence that this type of treatment should be offered more widely.
It was outlined in the UK government's 2008 Drug Strategy, subject to the results from this trial.
He added that although more expensive than conventional treatments, heroin therapy is considerably cheaper than imprisonment.
A Department of Health spokesman said any approach that gets people off drugs for good should be explored.
"We will look at evidence and both the clinical and cost effectiveness of these treatments.
"However, it is vital that we do all we can to prevent people using drugs in the first place."
Dr Roy Robertson a reader in the Department of Community Health Sciences at Edinburgh University, said whilst none of the outcomes are close to achieving abstinence, treatment with supervised injectable heroin "seems to be our best option".
"This is the intensive care for those heroin users who have failed after all sorts of other available treatments and continue to inject."
DrugScope chief executive Martin Barnes added that there is no "magic bullet" and several treatment interventions may be needed before someone becomes drug free or cuts down their drug use.
"On the basis of the outcomes described, there is a strong case for extending heroin prescribing as a carefully targeted and closely supervised form of treatment for chronic addiction."