The aims of the present study were to evaluate the prevalence and patterns of permanent tooth agenesis in individuals with Down syndrome, using meta-analysis methodology. Two independent investigators carried out a literature search to locate articles pertaining to permanent tooth agenesis in individuals with Down syndrome. The outcomes of interest were the prevalence and pattern of permanent tooth agenesis. Thirteen articles were selected for inclusion. The estimated overall prevalence of permanent tooth agenesis, excluding third molars, was 54.6% (95% CI: 44-66%). Considerable heterogeneity was present across the studies. Among subjects with tooth agenesis, approximately half had three or more missing teeth. The permanent teeth with the highest prevalence of agenesis were the maxillary lateral incisor (27%), mandibular second premolar (21%) and maxillary second premolar (18%). The single most commonly absent tooth, however, was the mandibular left second mandibular premolar (19.9%), followed by the maxillary left lateral incisor (19.4%). Little data describing specific tooth-agenesis patterns were available. In conclusion, individuals with Down syndrome display high prevalence rates and severity of agenesis of permanent teeth. Proper and timely diagnosis of missing permanent teeth is thus necessary, to allow a more comprehensive long-term treatment plan and a more favorable prognosis in these individuals.