Acute asthma is characterized by acute air way obstruction episodes presented as short breath, increased coughing, wheezing and difficult breathing, reversible with bronchodilator. It constitutes one of the most frequent causes of pediatric ER visits whose diagnosis and treatment is not always adequate. It is necessary to carry out a complete medical history searching for the number of previous attacks, risk factors, associated illnesses, triggers, prior hospitalizations, preventive and maintenance treatment used, along with a complete physical examination. During the management of moderate-severe attacks frequent systematic assessments are required to ensure treatment response. In children above 5 years old, monitoring of expiratory peak flow (EPF) during mild-moderate attacks is recommended. In general, a national consensus to classify and treat acute asthma in emergency services does not exist for which the need to develop a clinical practice guide of diagnosis and management arises.