Experts have recorded a positive outlook on the rising number of Australians seeking treatment to get off heroin addiction. However, it also reveals the nation's sporadic heroin supply.

From 2004 to 2007, the number of drug addicts entering treatment programs nationwide remained stable at about 38,800 but this increased to 41,347 in 2008.

Latest figures released by the Australian Institute of Health and Welfare (AIHW) on Wednesday show the figure jumped again to 43,445 in 2009.

Professor Steve Allsop, director of Curtin University's National Drug Research Institute said that there were mixed reasons for the rising number of Australians going for heroin treatment.

He said the reasons could be due to law enforcement and the availability of heroin.

Professor Allsop said that there had been a significant drop in the bulk importation of heroin into Australia about 2000. This means that supply of heroin will be scarce and heroin user may find it to be a hassle to look for them.

Prof Allsop also said the figures showed how efforts to broaden access to treatment programs, by involving GPs, were working.

I think it's all of those factors, he said.

(Overall) we're not seeing a very large increase in people consuming but are seeing a large increase in people getting into treatment - that's a good outcome.

Treatment clinics dispense opioid substitutes - mostly methadone but also buprenorphine or a combination of buprenorphine and naloxone - designed to curb an addict's craving with a minimal or no high.

The latest AIHW figures show men continue to account for 65 per cent of those in treatment, but there was a trend towards increasingly older clients.

In the study, it was found that the common age seeking the treatment were those of aged 30 to 39.But there was a rising percentage of 40 to 49 year-olds and reducing proportion of 20 to 29 year-olds.

Prof Allsop said treatment was a chance to stabilise a drug user's life, a process that often took years, and the ageing trend also indicated fewer people were fatally overdosing on heroin.

We see people now in their late 50s and early 60s in numbers that we did not used to see, he said.

There were 30,237 Australians in the treatment programs a decade ago, in 2000.