This study determines the relationship between the black market price for heroin and its corresponding purity in Australia for the period from July 1996 to June 2003 (seven years). The study used regression and correlation analyses to test the relationship between the two variables. If a negative relationship was found, then it would suggest that law enforcement operations were effective. However, the study determined that there was a near-zero correlation (r Â¼ 0.02) at commercial level (i.e. weights of one ounce) but a moderate relationship (r Â¼ 0.37) at user level (i.e. weights of 1 g).From this it was concluded that Australian law enforcement operations targeting commercial quantities were neither effective nor ineffective; but operations targeting street-level users were noticeably ineffective. To improve success at both levels, the study put forward the proposition that more aggressive enforcement operations in front of the international Customs barrier may be needed.