But researchers say increasing numbers of steroid users in Australia are oblivious to the severe health risks linked to performance-enhancing drugs, including cardiovascular disease, reproductive failure, liver damage and high levels of aggression.

''The irony is that steroid users are often health-oriented, but they're using a drug that is damaging their bodies to the point it could kill,'' says study leader Shane Darke, a professor at the national drug and alcohol research centre at University of NSW.

The study examined 24 deaths in NSW men aged 22 to 48 over the past 17 years where steroids were found in the system of the person who had died.

Nearly all men - most employed as personal trainers, body builders and security guards - showed obvious signs of chronic steroid abuse, including overdeveloped muscles and shrunken, scarred testicles.

''These men are doing major damage to their hearts and are substantially increasing their risk of death,'' Professor Darke said. ''For a very young group in their early 30s, their cardiac health looks like what you would expect of someone twice their age.''

He said more than half the men analysed had shrunken testicles, which is likely to impair the reproductive system.

While steroids were not the direct cause of death, 62.5 per cent of men died from taking toxic amounts of steroids together with other illicit drugs - including cocaine and methamphetamine - either alone or in combination with heart disease. More than half had serious heart disease, including thickened arteries and damaged heart muscles.

About a quarter of deaths were caused by suicide or homicide, said Professor Darke, which links long-term steroid use with an increased risk of aggressive and violent behaviour.

''The idea of 'roid rage' works in both ways,'' he says. ''They can be raging against themselves - or others. It might be helpful for steroid users to realise that mood swings, paranoia and suicidal thoughts are probably coming from steroids.''

Jamie Close, a 42-year-old personal trainer, stopped taking steroids after health practitioners warned he had early signs of liver damage and adrenal exhaustion.

He began using steroids at 28 while running a gym at Brighton Le Sands, increasing the use from weekly to once-a-day injections.

''I didn't have any idea about the health risks. I was a bit naive.''

Professor Darke said this analysis provided a glimpse into the ''hidden'' world of steroid use.