OBJECTIVE: Attention-Deficit/Hyperactivity Disorder is a very prevalent disorder in children and adolescents determining important impairments in those affected. This review aims to discuss some clinical and therapeutic dilemmas found by clinical psychiatrists in the treatment of the disorder. METHODS: This is a comprehensive, non-systematic review of the literature addressing the following issues: a) differentiation normality/presence of the disorder; b) clinical relevance of the age-of-onset of impairment criterion; c) frontiers with Bipolar Disorders (BD); d) guidelines for treatment when the disorder is associated with comorbidities. RESULTS: Clinical tips are presented to make the diagnosis without significantly increasing the proportion of false-positives, as well as to help in both the differential diagnosis with BD and the pharmacological management of the disorder associated to comorbidities. CONCLUSION: The precise diagnosis, avoiding very flexible criteria, is crucial in a disorder with a dimensional construct in the population, as well as the adequate use of medication for a highly comorbid disorder.