Your doctor tests your urine for your protection as well as his.  A recent study showed that 77% of chronic pain patients were not taking their medications as their doctor had prescribed them.  (Read "Pain Meds – Are You Following Doctor's Orders?")    Oxycodone is a Schedule II narcotic with a high potential for abuse.  When a patient is tested, too much of the drug in their system could indicate that it is being abused; none of the drug in their system could indicate that the patient might be selling it.  If the doctor continues prescribing an opioid without testing to be sure it is being taken correctly, he runs the risk of being prosecuted, imprisoned and losing his license should the DEA discover that some of his patients are abusing or selling the drugs.    Not taking opioids as prescribed can also be dangerous for the patient.  Testing can alert the doctor to potential problems so they can be corrected before serious damage is done.   Karen