This chapter looks at otitis. The clinical burden from acute (AOM) and chronic suppurative otitis media (CSOM) and their associated morbidities is substantial, especially in children. In industrialized countries, AOM remains the most frequent reason for pediatric office visits and recurrent otitis media (ROM), or persistent middle ear fluid and associated hearing loss, reduces quality of life. In developing nations, infectious complications of AOM include suppurative intracranial infection and CSOM with severe hearing loss. The prescription of antimicrobials increases bacterial resistance, so the role of antimicrobials in AOM has been reevaluated, using an evidence-based approach. ROM and CSOM usually begin in the first year of life, due to Streptococcus pneumoniae, nontypeable Haemophilus influenzae (NTHi), or Moraxella catarrhalis.