Background: Emergency Department (ED) is considered to be the heart of a hospital. Based on many studies, a well-organized physical environment can enhance efficacy. Objectives: In this study, we aimed to investigate the influence of physical environment in EDs on efficacy. Materials and Methods: This analytical cross-sectional study was conducted via the faculty members of the ED and residents of Shahid Beheshti University of Medical Sciences in Tehran, Iran. Data were collected using a predefined questionnaire. Descriptive statistics and ANOVA were used to analyze the data. Results: Sixty-two participants, including 21 females and 41 males, completed the questionnaires. The mean age of the participants was 37 years (SD: 8.42). The mean work experience was 8 years (SD: 4.52) and all the studied variables varied within a range of 3.3 - 4.2. Time indices had the highest mean among variables followed by capacity, work space, treatment units, critical care units and, triage indices, respectively. Conclusions: In general, time indices including length of patient stay in the ED and space capacity, emphasizing the need to address these shortcomings.