The aim of this study is to determine delta 9 tetrahydrocannabinol (delta9 THC) content in 5227 seizures of cannabis products over the period 1997-2004 (first four months). The products were seized in Modena country (Italy). The samples were classified as marijuana and hashish and divided into subgroups. The following results show an increase in the potency (concentration of delta9 THC) of these products.