Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Objectives: We aimed to determine the effectiveness of pneumococcal vaccines on otitis media (OM) and acute otitis media (AOM) in children. Methods: We conducted a systematic search in databases PubMed (MEDLINE), Embase, Lilacs, and Web of Science. We included observational studies that evaluated any pneumococcal vaccine – including 7, 10, and 13-valent pneumococcal conjugate vaccines (PCV7, PCV10, and PCV13) and 23-valent polysaccharide vaccines (PPSV23) as the intervention, in children aged less than five years. Results: Out of the 2112 screened studies, 48 observational studies complied with the eligibility criteria and therefore were included in this review. Of the included studies, 30 (63%) were before-after, eleven (23%) cohort, six (13%) time series, and one (2%) case-control study designs. Vaccine effectiveness (VE) in preventing OM or AOM varied by vaccine type. In children under 24 months VE ranged from 8% and 42.7% (PCV7), 5.6% to 84% (PCV10) and 2.2% to 68% (PCV13). In children aged less than 60 months, VE ranged between 13.2% and 39% for PCV7, 11% to 39% for PCV10 (only children under 48 months), and 39% to 41% (PCV13). Conclusions: Our results demonstrate significant effect of pneumococcal vaccination in decreasing OM or AOM in children under five years old in several countries supporting the public health value of introducing PCVs in national immunization programs