Background The coronavirus disease 2019 (COVID-19) pandemic has engendered difficulties for health systems globally; however, the effect of the pandemic on emergency medicine (EM) residency training programs is unknown. The pandemic has caused reduced volumes of emergency department (ED) patients, except for those with COVID-19 infections, and this may reduce the case exposure of EM residents. The primary objective of this study was to compare the clinical exposure of EM residents between the prepandemic and pandemic periods. Methods This was a retrospective study of EM resident physicians’ training in a tertiary teaching hospital with two branch regional hospitals in Taiwan. We retrieved data regarding patients seen by EM residents in the ED between September 1, 2019, and April 30, 2020. The first confirmed COVID-19 case in Taiwan was reported on January 11, so the pandemic period in our study was defined as spanning from February 1, 2020, to April 30, 2020. The number and characteristics of patients seen by residents were recorded. We compared the data between the prepandemic and pandemic periods.Results The mean number of patients per hour (PPH) seen by EM residents in the adult ED decreased in all three hospitals during the pandemic. The average PPH of critical area of medical ED was 1.68 in the pre-epidemic period and decreased to 1.33 in the epidemic period (p value < 0.001). The average number of patients managed by residents decreased from 1.24 to 0.82 in the trauma ED (p value= 0.01) and 1.56 to 0.51 in the pediatric ED (p value=0.003) during the pandemic, respectively. The severity of patient illness did not change significantly between the periods. Conclusions The COVID-19 pandemic engendered a reduced ED volume and decreased EM residents’ clinical exposure. All portion of EM residency training were affected by the pandemic, with pediatric EM being the most affected. The patient volume reduction may persist and in turn reduce patients’ case exposure until the pandemic subsides. Adjustment of the training programs may be necessary and ancillary methods of learning should be used to ensure adequate EM residency training.