Objective: To explore impact of emergency medicine residency program on patient waiting times in emergency department (ED) and determine the associated factors.Methods: A two-phased sequential exploratory mixed-methods approach was used. The first phase was comprised of retrospective before-after design of ED encounters for a 3-month period, six months before and six months after the introduction of an emergency medicine residency program in an Iranian teaching hospital. The second phase included semi-structured interviews with five individuals which purposively selected to participate in qualitative design. Quantitative data were analysed descriptively and qualitative data were analysed using an iterative framework approach.Results: The most patients were admitted to the hospital in night shift, both before and after the resident EMS. No statistically significant differences were found among all of the waiting times during the two time periods except for the average time interval between admission and physician start time (p<0.0001), which increased (instead of reducing), and the average time interval between physician start time and first treatment measure (p<0.0001), which decreased during the year the residents began. The interviewees revealed the intradisciplinary conflicts and interferences existing between ED and other specialist departments, are main important factor to delayed processing of patients visits.Conclusion: This study has shown that intradisciplinary conflict would affect the outcomes of emergency medicine residency program and ED process. These new findings enhance the understanding of the nature of conflicts and will persuade policy makers that design a set of clinical practice guidelines to clarify the duties and responsibilities of parties involved in ED.