ABSTRACT: Background In some countries the misuse and diversion of prescribed opioid analgesic is increasing considerably, but there is no official data regarding the situation in Colombia. The aim of this study was to identify all dependent to opioid analgesics legally prescribed patients that were treated in a University Hospital in Medellin, Colombia during 4 years and to characterize this population. Methods Observational study in a University Hospital in Medellin, Colombia, searching for patients with ICD-10 codes related with opioid related disorders, adverse events or pain and treated between January 2011 and December 2014. Results Sixty patients with opioid dependence according to DSM-IV criteria were found from 3332 clinical charts reviewed. The median age was 43 years. Although all patients met the DSM-IV criteria, 33 % of patients were wrongly diagnosed by other ICD-10 codes. Almost all patient (88 %) initiated opioids after medical prescription although the adherence to pain scale was low (25 %). The median time of consumption was 48 months. Tramadol was the opioid more frequently used by patients, followed by morphine and oxycodone. A statistically significant higher consumption of other psychotropic substances was observed in male than female (P = 0.005 by Fisher’s test). After be diagnosed, 55 % of patients gone a methadone-based replacement therapy. Conclusion Legally prescribed opioid dependence was belatedly diagnosed in 60 patients in a University hospital, after prolonged use of drugs to treat chronic pain and with low adherence to pain scale or guidelines. This is the first report in Colombia.COL0005744