The aim of this study was to characterize first-time oxycodone and morphine prescriptions in outpatients by type of prescriber and naivety in regard to strong opioids. All prescriptions for morphine and oxycodone in Denmark reported to the National Register of Medicinal Product Statistics in 2010 were analysed. If a patient had not had a prescription filled for the same drug within the last 2 years, the prescription was defined as a first-time prescription. Patients who had not received a prescription for strong opioids for 6 months prior to the date of redemption were classified as strong opioid naive. The odds ratio (OR) was calculated to investigate whether general practitioners (GPs) and hospital physicians had similar preferences for oxycodone over morphine for strong opioid-naive patients. We included 69,110 first-time prescriptions, of which 59,316 (86%) were for strong opioid-naive patients. Opioid-naive patients received 79% of the first-time prescriptions for morphine and 91% of the prescriptions for oxycodone. Hospital physicians had a greater preference for oxycodone over morphine than GPs (OR 1.34, 95% CI 1.29-1.39). However, GPs were responsible for approximately 61% of all first-time prescriptions for both oxycodone and morphine for strong opioid-naive patients. In conclusion, oxycodone is to a great extent prescribed as the first-choice strong opioid, and both GPs and hospital physicians seem to contribute to this prescribing pattern of strong opioids to outpatients.