Benefits of early palliative referral in oncology are well documented. Palliative care referral "triggers" may help identify patients for referral. Many triggers have been proposed, but are not commonly used. This study reviewed the timing of palliative care involvement for patients in a tertiary referral oncology hospital, and whether the use of a trigger tool prior to admission would have facilitated earlier referral. This was a retrospective cohort study of cancer patients who died during an unplanned admission between November 2014 and October 2015. A literature review identified seven palliative care referral tools which were included in this analysis, and compared by identifying common themes. Each tool was applied to patients by reviewing electronic patient records. Timing of palliative referral and whether patients met any triggers within 6 months before their terminal admission were assessed. A total of 159 patients were identified. Forty-six percent were referred to palliative care prior to terminal admission. Application of 6 out of 7 trigger tools would have resulted in the majority of patients (up to 91.2%) referred to palliative care prior to admission. Most patients (52.2%) were referred only during their terminal admission. Patients known to palliative care before admission (N = 73) were reviewed quicker than those who were not (N = 86) (median (range) 1 day (0-23 days) versus 5 days (0-59 days), p < 0.00001). In this patient cohort, a palliative referral trigger tool may have proactively identified most patients prior to their terminal admission. Prospective testing of trigger tools in oncology populations is warranted.