BACKGROUND: Chest compression fraction (CCF) is the cumulative time spent providing chest compressions divided by the total time taken for the entire resuscitation. Targeting a compression fraction of at least 60% is intended to limit interruptions in compressions and to maximize coronary perfusion during cardiopulmonary resuscitation. Our aim was to identify the mean CCF and its relationship with various factors affecting it. METHODS: Patients presenting to the emergency department in cardiac arrest at a single center was prospectively included in this study. Resuscitation was provided by trained healthcare providers. The feedback device Cprmeter2™ was placed on the patients’ sternum at the beginning of resuscitation. The total time taken for entire resuscitation was noted by the device and CCF calculated. RESULTS: The mean CCF was analyzed using descriptive statistics and was found to be 71.60 ± 7.52%. The total duration of resuscitation (R= -0.55, p= <0.001, min-max 2.02-34.31, mean 12.25 ± 6.54), number of people giving chest compressions (R= -0.48, p= <0.001) and total number of team members in resuscitation (R= -0.50, p= <0.001, min-max 4-10, mean 6.65) had negative correlation with CCF. Diurnal variation (day, n=35; mean 69.20±7% and night, n=20; mean 75.80±5.6%, p= 0.001) and patients receiving defibrillation (receiving n=10 mean 67.00±4.11% & not receiving n=45 mean 72.62±7.42%, p= 0.005) were found to significantly affect CCF. CONCLUSION: The mean CCF for cardiac arrest patients was well within the targets of guideline recommendation.CCF decreased when resuscitation lasted longer, during day time, when defibrillator was used, and when the total team members and number of people giving chest compressions increased. If these factors are properly monitored and interventions made accordingly, the CCF during resuscitation may improve. Keywords: Cardiac arrest, CCF, CPR, defibrillation, Emergency Department CTRI registration number: CTRI/2018/05/013913, registration date: 16/05/2018