Moraxella catarrhalis is part of the normal bacterial flora in the nasopharynx of children, although over the past two decades, it has emerged as a significant bacterial pathogen and not simply a commensal colonizer. Moraxella catarrhalis is a common bacterial species cultured from the nasopharynx of children during otitis media episodes, with the patterns of nasopharyngeal colonization by microorganisms being important determinants for otitis media disease. Treatment of otitis media is not always appropriate, and the long-term overuse of antibiotics in otitis media reduces the effectiveness of treatment and places children at an increased risk of antibiotic-resistant infections. Because there is currently no ideal treatment for otitis media, an alternative to the use of antibiotics is vaccination. To date, several Moraxella catarrhalis vaccine candidates have been described, which may be effective in reducing the burden of otitis media disease.