Background: Emergency Response Time is an interval between call receipt and arrival of the firstrnEmergency vehicle to the scene which should be less than 8 minute. As a result of the emergingrnsignificance of time-sensitive medical emergencies such as cardiac arrest, stroke, and acuternmyocardial infarction and nonmedical emergency like trauma, it has been the leading measure ofrnEmergency Medical System performance quality in many countries. Despite its importance, littlernwas studied about the ERT and associated factors. Therefore, this study aims to determine thernEmergency Response Time (ERT) and identify associated factors in Addis Ababa, Ethiopia 2019. rnMethod: Facility based cross-sectional study design was conducted in Addis Ababa City Fire andrnEmergency Prevention and Control Authority and Red Cross Association ambulance service, fromrnApril 2019 to May 2019. Data was collected by observation and interview using structuredrnchecklist. Then it was cleaned, coded, entered in to EPI data v.3.1 and exported to SPSS versionrn25 statistical package for analysis. Descriptive statistics used in order to describe data and bothrnbivariate and multivariable logistic regression used to examine associated factors. A factor with pvaluern 6 km AOR 17.34 (7.16, 41.98), dispatchrntime interval >2 min AOR 15.79 (5.95, 41.93) and heavy traffic conditions AOR 16.33 (4.49, 59.43)rnare found to be the major determent factors of ERT. Age, level of consciousness, severity of thernillness and weather condition were also shown significant association. rnConclusion and recommendation: The mean emergency response time interval was above thernstandard and the majority of the patients were transported under delayed ERT. Scene distance,rndispatch time interval, heavy traffic condition, time of call, and has shown associations. Actionrnlike pre-allocation of ambulance, installing emergency communication device, drivers and publicrnawareness creation and training to ambulance nurse should be done to decrease ERT.