Introduction:Background: Ischemic ventricular fibrillation (VF) is highly related to ST elevation myocardial infarction (STEMI). Pre-hospital STEMI patients have been shown to also develop VF during ambulance transport. However, there is limited literature exploring the characteristics of this specific population of VF. Objective: To determine the incidence of pre-hospital VF, and evaluate some demographic and electrocardiogram (ECG) characteristics of STEMI patients having VF while transported by ambulance in a Quebec suburban pre-hospital setting. Methods: A retrospective study from 8th August 2006 to 6th December 2015 of 937 STEMI patients transported by ambulance in the Chaudiere-Appalaches region, south of Quebec City. Destination for treatment was either Catherization Laboratory (CL) or the nearest Emergency Department (ED) for reperfusion treatment and was mainly based upon a maximum transport time of 60 minutes, from the first confirmed STEMI-ECG to the CL. Demographics and ECG characteristics were extracted from the patients care records. SPSS-20 was used for descriptive statistics. Results: 937 patients (259 women & 678 men) diagnosed with STEMI were included in the study. Patients were regrouped in V1-V4 leads STEMI (336; 35.9%) and in other leads STEMI (651; 64.1%). 52 (5.55%) of all STEMI patients had FV during ambulance transport. There were 10 women (27,4%) and 42 men (72,6%). Of these, 28 had V1-V4 STEMI (28/336; 8.33%) while 24 had other leads STEMI (24/651; 3.69%). Relative risk of FV is higher (225%) with V1-V4 STEMI compared to other leads STEMI. Regarding age groups, patients from 60 to 70 years old represent 38.4% (20/52) of FV for 25.7% (241/937) of STEMI patients while those over 80 years old had 3.85% (2/52) of FV, but were 17% (159/937) of all STEMI patients. Men seem also more at risk for FV (16/20) especially between 60 and 70 years old compare to other age group. Conclusion: In this suburban area, VF occurred in 5.55% of STEMI patient’s transported by ambulance. STEMI patients over 80 years old had a low rate of FV. Being a man, 60 to 70 years old, with a STEMI located in V1-V4, seems to be associated with a higher risk of VF. More studies are needed to confirm these results and explore other characteristics associated to pre-hospital VF.