Urinary tract infection (UTI) has a prevalence of 2-5%, and an incidence of 5-8% in children under 5 years of age, with 80-90% of its aetiology being E. coli. The definitive diagnosis is made by urine culture, although Gram stain is recommended for immediate therapeutic decisions, with a sensitivity of 100% and a specificity of 87%. This study analyses the benefits of this type of procedure and avoids the mismanagement of antibiotics in the paediatric population.