Gut microbiota is defined as microbes that collectively inhabit the gut ecosystem. Several factors, including diet, age, birth mode, breast-feeding or formula-feeding, geography, exercise, alcohol consumption, and exposure to antibiotics may influence gut microbiota. Previous conventional culturing together with recent culture-independent molecular studies show that vegan diets appear to affect gut microbiota. Furthermore, recent literature also indicates that vegan diets may have various health benefits, including amelioration of metabolic syndrome, cardiovascular disease and rheumatoid arthritis. Authors conclude that these findings have their limitations. Thus, further research may help to clarify the complex mechanisms and interrelationships between vegan diets and gut microbiota.