Objectives: To compare trends in substance use as reported by the Australian and U.S. national household surveys from 1995-2007 and to highlight areas of concern in both countries.

Methodology: The U.S. data were adjusted to match the Australian sample of ages 14 and older.

Results: Since 1998, the proportion of Australians who had used any illicit drug in the past year decreased significantly, while use in the U.S. is unchanged. Levels of past-year use of “any illicit drug,” cannabis, and heroin were similar in both countries in 2004. While amphetamine and methamphetamine are the most common “uppers” in Australia, cocaine is the most frequently used “upper” in the U.S. In both countries, except for teenagers, males were more likely than females to have drunk in the past year. There has been no significant difference in past-year drinking between girls and boys since 1998. Australian girls and boys have not differed in their levels of past-year use of “any illicit drug” since 1998, and U.S. girls caught up with boys in 2004. There has been no difference in levels of use of ecstasy or heroin between girls and boys in either country since the 2001 surveys. Among all U.S. age groups, teenagers had the highest levels of past-year use of any illicit drug, cannabis, and stimulants in 2004, while in Australia, persons in their twenties had the highest past-year use of these drugs.

Conclusions: Girls in both countries are drinking at the same rates as boys and using many drugs in similar or higher rates. This increasing use by girls warrants targeted efforts. The higher levels of use by U.S. teens, as compared to persons in their twenties, may be a predictor of additional treatment needs both for adolescents now and for young adults as this population group ages.