Technological progress in high-throughput sequencing and advanced bioinformatic techniques, have facilitated a deeper understanding of the gut microbial influence on human health. Collectively known as the gut microbiota, the trillions of microbes including bacteria, viruses and fungi, which reside within the gut, are now recognised as significant contributors to human (host) health. Patients with non-communicable diseases such as metabolic syndrome, obesity and inflammatory bowel disease, demonstrate distinct microbial alterations. This has prompted vigorous pursuit of the mechanisms by which this microbial ‘organ’ influences host health. This branch of medicine has already revealed exciting avenues for disease treatment, from the discovery of novel antibiotics to the treatment of recurrent Clostridium difficile infection. The scale and spectrum of microbial influence is substantial and elegant studies have linked the presence or absence of specific microbes with immunity, neurodevelopment and even behavioural disturbances. The potential impact of microbiome science extends to the specialties of Sports Medicine and particularly to Exercise Medicine