The aim of this article is to describe the drug career of 71 severely opioid-dependent women who had a history of selling sex and were enrolled in methadone maintenance treatment. Data were collected through semi-structured interviews, from medical records and reports from social agencies and correctional institutions. The sequential pattern could be described in the following order: initiation of the first drug of abuse, opioid onset, initiation of selling sex, first non-methadone treatment episode, first sentence and, finally, methadone maintenance treatment. There were significant age differences and correlations between most of the events. The main correlation (r = 0.70) was the one between debut of opioid use and selling sex, which was confirmed in a stepwise multiple regression analysis. In addition, a history of running away from home advanced the age at which the women started selling sex for those with an onset of opioid use at an older age than the mean of 18.4 years.