Aim and objectives: To describe the ideal doctors' shift handover process in a systematic fashion, and to identify tasks that should be performed, but are not consistently done. To understand the types of communication problems that may occur during the handover process, their causes, their likelihood of occurrence and their effect on patient safety. Method: Three studies were conducted in two, Scottish Acute Medical Units. A Hierarchical Task Analysis was performed and data was collected by means of interviews and focus groups. Observations of doctors' actual shift handover process were compared against the description of doctors' ideal handover process. To examine potential failures modes, a Healthcare Failure Modes and Effects Analysis was performed using focus group interviews. Results: The handover process entailed the pre-handover, the handover, and the post- handover phases. Multiple critical steps in the process were omitted by outgoing shift doctors. The pre-handover was particularly vulnerable to information omission, with over 50% of its critical tasks not being performed across a total of 62 observations. Nonetheless, most of these omissions were typically caught during the handover meeting, especially if incoming doctors participated in pre-handover activities. Post-handover activities involved prioritizing and delegating clinical tasks. However these were observed not to happen consistently due to multiple interruptions. Thirty-four failure modes were identified, with eight of them posing a significant risk to patient safety. The studies found that interruptions, patient workload, and a lack of standardised procedures were the biggest causes for information loss during the handover process. Conclusions: There are key critical tasks necessary for an ideal doctors' shift handover process. A simple, handover process checklist may ensure critical handover tasks have been achieved prior to any shift change. Interruptions, patient workload, peer trust, and a lack of standard operating procedures are areas that future handover research should examine.