This study, undertaken in the National Drug Treatment Centre in Dublin, took place against the backdrop of a perceived increasing problem with benzodiazepine co-abuse in the opiate-dependent population of Dublin. The authors contended that early detection of this co-abuse was essential in order to combat the increased risk of dangerous injecting practices, such as sharing of needles. This study aimed to describe the difficulties in identifying the co-abuse of benzodiazepines in a cohort of opiate-dependent patients. They found that standard methods of urinalysis failed to identify 10% of co-abuse, and treatment to minimise the consequences of the co-abuse was not implemented at the earliest time possible.