Introduction: Peripheral venous access is the most common procedure performed in the emergency department. Different factors can be a source of difficulty for this procedure. Our objective was to identify these factors in an emergency department.Method: This was a prospective observational study carried out over a period of six months in an university emergency department. All adult patients admitted to the emergency department who required a peripheral venous line to be inserted by the traditional method were included in this study. For each patient, socio-demographic characteristics, clinical examination data, history and type of operator were recorded. Difficulty was judged on the number of attempts necessary for successful venous access. Predictive factors were identified by binary logistic regression.Results: Over the 6-month period analyzed, 1007 forms were usable. The population was divided into two groups, Gr.IVA.E: n=681 (67,6%) and Gr.IVA.D: n=326 (32,4%). were retained as predictive of difficulty: moderate obesity, type of provider of the procedure: young physician, reactivity/pain to the procedure, size of cannula (18G), recent admission within 3 months and clinical examination data (burns, neurological deficit, arteriovenous fistula, swelling of extremities).Discussion: The identification of the factors that make peripheral venous access difficult in the emergency department can lead to an improvement in the quality of care and therefore to better management. Good clinical assessment, mastery of alternatives to the traditional technique, adoption of medical simulation for learning, and adoption of a clinical score can overcome this difficulty.