Pre-operative opioid use is common and should be considered a comorbidity among surgical candidates. Our objective was to describe the rate of pre-operative opioid use and patterns of post-operative outpatient opioid prescribing in a cohort of gynecologic oncology patients. A retrospective cohort study was conducted with 448 gynecologic oncology surgical patients undergoing surgery for a suspected or known cancer diagnosis from January 2016 to December 2016. Pre-operative opioid users (n=97) were identified. Patient and surgical characteristics were abstracted, as was post-operative opioid prescription (type of opioid, oral morphine equivalents amount) and length of stay. For pre-operative opioid users, the type of opioid prescribed post-operatively was compared with the type of pre-operative opioid. Pre-operative opioid users were compared with non-users, stratified by surgery type. Descriptive statistics were analyzed using χ statistic, and medians were compared using a Mann-Whitney U statistic. Pre-operative opioid prescriptions were noted in 21% of patients, and 24% of these had two or more opioid prescriptions before surgery. The majority of pre-operative opioid users (51%) were maintained on the same agent post-operatively at the time of discharge, but 36% were switched to a different opioid and 7% were prescribed an additional opioid. Overall and in laparotomies, pre-operative opioid users received higher volume post-operative prescriptions than non-users. There was no difference in post-operative prescription volume for minimally invasive surgeries or in length of stay between pre-operative users and non-users. Pre-operative opioid use is common in gynecologic oncology patients and should be considered during pre-operative planning. Pre-operative opioid use was associated with a higher volume and wider range of post-operative prescription. Over 40% of opioid users were discharged with either an additional opioid or a new opioid, highlighting a potential missed opportunity to optimize opioid safety. Further research is needed to characterize the relationship between pre-operative opioid use and peri-operative outcomes and to develop strategies to manage pain effectively in this population without compromising opioid safety.