Background The phenomena of missed nursing care is usually measured through quantitative surveys that detail the specific tasks that are rationed or delayed, and the reasons why this is so. These studies report high levels of agreement within and across countries between the two major measures employed; the Kalisch's MISSCARE tool and the RN4Cast Basel Extent of Rationing of Nursing Care (BERNCA) instrument. Most of these studies have been conducted in acute care settings and demonstrate the impact of lack of human and other resources upon decisions to omit care. Less in known about missed care in residential aged care Aim To explore the frequency and causes of missed care in residential aged care in three Australian states: New South Wales, Victoria and South Australia. Methods Quantitative and qualitative data from 922 respondents working in residential aged care to the MISSCARE survey were bought together to identify the tasks missed in aged care and reasons for this. Findings Respondents report the omission of unplanned care (toileting and answering bells) and rehabilitative care. The primary reasons for missed care are staffing shortages and difficulties in meeting residents’ complex health care needs due to demands arising from increased resident acuity and fewer skilled nurses to meet this demand. Conclusion Resident care is missed in residential aged care with staffing numbers identified as a key cause.