Introduction: The number of emergency department (ED) visits across Ontario has increased annually over the past two decades leading to overcrowding and longer wait times. ED volume forecasting may provide insight to strategic planners regarding future patient volumes and the effects on health care resources. We investigated the pattern of ED use at the local health integration network (LHIN) level and developed forecasts using historical data. The forecasts were then used to examine the effect on acute care hospital bed requirements and the number of full time equivalent physicians needed. Methods: Aggregated data from the Canadian Institute for Health Information for the period 2003 to 2013 was obtained for each of Ontario’s LHINs. The total number of ED visits per year was first quantified by LHIN and then simple linear regression was used to forecast patient volumes in 2018 and 2023. The rate of hospital admission by LHIN was also calculated. We then used the forecasted volume, admission rate and the total number of acute care hospital beds by LHIN to predict the total number of beds needed by LHIN. Based on the forecasted patient volumes and the hours of coverage model, the total number of full-time equivalent physicians needed was calculated. Results: Over the study period, the number of patients increased from 4 to 37% among LHINs. Admission rates generally decreased from 2003 to 2013. Based on historical trends, all EDs across Ontario are expected to experience increased patient visits in the future but at different rates of growth. Depending on the rate of growth in ED visits, the number of acute care beds needed by LHIN is somewhat variable and affected by the proportion of alternate level of care patients. Given, the forecasted increase in patient volume, the hours of coverage model suggests that approximately 320 additional full-time equivalent ED physicians are needed across the province by 2023. Conclusion: Although all forecasts inherently have a degree of error associated with their estimates, strategic planners require some quantitative prediction of future events to develop initial plans. Through research, these predictions can be focused and refined. The results suggest that many hospitals will experience increased demand for services and will have to do resource allocation planning accordingly to ensure patient demand is met appropriately.