Methods: The investigators will conduct a pragmatic, multi-centre, (hospital, inpatient hospice, community hospital) open-label randomised-controlled trial comparing the use of Haloperidol versus Olanzapine in advanced cancer or end-stage organ disease patients with hyperactive delirium. The primary outcome is the change in Richmond Agitation and Sedation Scale (RASS) scores among patients in each treatment group at 8 hours post-drug administration. The secondary outcome is the control of hyperactive delirium at 24, 48 and 72 hours using either Haloperidol or Olanzapine. The mean doses of Haloperidol and Olanzapine used as well as the volume of rescue Midazolam required as well as side-effects of the study medications, survival after enrolment into study will also be studied. 4. Significance to palliative care The results of this study will advance the knowledge of delirium management worldwide with regards to the efficacy of Haloperidol and Olanzapine in managing hyperactive delirium in patients with advanced cancer or end-stage organ disease. Haloperidol is used traditionally in palliative care for managing delirium. However, as a conventional anti-psychotic, it does cause extra-pyramidal side-effects. Olanzapine, a newer atypical anti-psychotic with a more favourable side-effect profile is being used increasingly in the control of delirium. These 2 commonly used drugs have never been compared head to head in a randomised-controlled, multi-centre study.