Genetics has long been considered to associate with many exercise-related traits and sport performance phenotypes. A genetic basis for elite international marathon running performance exists due to the heritability of endurance-related traits. This has prompted a generation of genomic study to identify marathon success. The aim of this study was to systematically review the evidence of genes, and their polymorphisms, that may play a role in marathon running performance. A search strategy was implemented on systematic databases following PRISMA guidelines. Studies were case-control, cohort or genome-wide association designs and provided data on the genotypes associated with elite marathon athlete status and/or marathon running performance. The search identified 241 studies, from which, 14 studies were deemed suitable for inclusion. A total of 160 different polymorphisms in 27 genes were identified in 10,442 participants, of which 2,984 were marathon distance runners. The review identified a possible 16 single nucleotide polymorphisms (SNPs) in 14 genes associated with marathon running performance. While multiple genes and their polymorphisms have been associated with marathon running performance, predicting future marathon success based on genomic data is premature due to the lack of replicated studies. There is limited replication of genotype-phenotype associations and there is possible publication bias, thus, further studies are required to strengthen our understanding of the genes involved in marathon running. Future research utilising genome-wide technologies in large cohorts is required to elucidate the multiple genetic factors that govern complex endurance-related traits and the impact of epigenetics should be considered.