There are strong reasons to support the practice of prescribing heroin to drug misusers, researchers claim.
Heroin is prescribed under strict rules
A University of Amsterdam team says the treatment is cost-effective, even though it is expensive.
The British Medical Journal study found the cost to health services was offset by savings linked to crime reduction.
Supervised medical prescription of heroin - a class A drug in the UK - is controversial. UK experts said a range of treatments should be available.
Previous research has shown supervised medial prescription of heroin improves the physical and mental health, and ability to function normally in society, of users who cannot be successfully treated using just methadone - a synthetic narcotic used to treat heroin addiction.
The Dutch scientists looked at 430 heroin addicts who were taking part in methadone maintenance programmes in six cities in the Netherlands.
Before they took part in the study, they had frequently engaged in illegal activities to acquire money or drugs.
The addicts were given either methadone plus heroin, or methadone alone.
The patients were then assessed after a year of treatment.
Those given the combination treatment reported a better quality of life, compared to those given methadone alone.
And although the costs of co-prescription were found to be considerably higher, they were offset by lower policing costs and reduced costs of crime against property because addicts were not breaking the law to fund their habit.
The average total net savings amounted to 12,793 euros (about £8,600) per patient per year.
The researchers, led by Dr Marcel Dijkgraaf, wrote in the BMJ: "From a societal perspective supervised medical prescription of methadone plus heroin is less costly than methadone maintenance treatment."
They said co-prescription was cost effective for patients who had previously failed to stick to treatment with methadone alone.
But a spokeswoman for the drugs charity Drugscope said: "It is not the case that one kind of treatment will work for all drug addicts: individuals respond with varying degrees of success to different treatment methods.
"It is therefore important that we have a range of treatment options available, including heroin prescribing."
She added: "The government has indicated in the past that it was in favour of extending heroin prescribing, but despite this, progress has been disappointingly slow.
"This study adds weight to the argument in favour of extending heroin prescription, showing that there are significant benefits to be had, not just in terms of health but also in terms of economic and social costs."