A range of aberrant drug-taking behaviours can occur in patients who are undergoing treatment for chronic pain, especially if opioid therapy is involved. Assessing and understanding these behaviours, and their relationship to addiction (or substance use disorder), can be difficult but it is necessary for assuring quality pain management. Aberrant drug-taking behaviour may be evident, for example, when a patient with pain is unilaterally escalating doses of opioids or using the medications to treat other symptoms or when prescriptions are being mishandled. In patients with a history of substance abuse, these are often serious developments to which a clinician must know how to react. These complex behaviours may be indicative of addiction or may be simply a reaction to under-medicated pain. The clinician therefore is challenged to understand such behaviours and plan interventions accordingly.Although it is becoming increasingly common to avoid opioid therapy in patients demonstrating such challenging behaviours for fear of regulatory scrutiny, clinical management can be tailored to address the many possibilities that might be giving rise to such behaviours. In addition, control over prescriptions can be accomplished without necessarily terminating the prescribing of controlled substances entirely. Optimal medical management of chronic pain in those patients with addiction problems or engaging in problematic behaviours involves careful, ongoing assessment by the clinician as well as a tailored management approach. This approach should use multiple structures including strict contracts, prudent drug selection and frequent follow-ups to pain and addiction treatments, including the use of urine toxicology screening, to maximise the likelihood of a good outcome.