There is strength in numbers. The 100 trillionstrong human-gut bacterial population, referred to as microbiota, validate this aphorism with the growing recognition of their effect on health and disease. 1 Over 500 of these gastrointestinal (GI) tract resident species have had their genomes, collectively known as the microbiome, identified since 2007, as part of the National Institutes of Health Human Microgenome Project. 2 These efforts have led to new clinical applications of these data. For example, microbiota composition can be used in the screening of colorectal cancer, improving the pretest to posttest probability of adenoma diagnosis more than 50-fold. 3 Manipulating microbiota has been shown in preliminary studies to assist in the treatment of irritable bowel syndrome, inflammatory bowel disease, and other GI diseases. 4-7 But perhaps more surprising is that gut microbiota are now increasingly understood to influence pathologies beyond their immediate colonic realm, including chronic diseases, such as asthma, obesity, and cardiovascular and renal diseases. 8 Even the central nervous system is not exempt from the effects of intestinal bacterial residents. The presence of epsilon toxin‐secreting Clostridium perfringens was reported to be a possible mechanism for emergent demyelinating lesions. 9 Furthermore, reductions in microbiota concentration with oral antibiotics delay the onset and reduce the severity of experimental allergic encephalomyelitis, the animal model of multiple sclerosis. 10 Within this context, the revelation that microbiota may influence a neurodegenerative disease such as Parkinson’s disease (PD) seemed all but inevitable. In this issue of Movement Disorders, Scheperjans and colleagues demonstrate that variations in gut microbiota can be found in PD patients and may contribute to its major clinical phenotypes. 11 The outcome of this first-of-a-kind case-control study showed a reduced abundance of the Prevotellaceae bacteria family in PD compared with healthy controls, and greater abundance of Enterobacteriaceae bacteria family among those with the postural instability and gait difficulty (PIGD) phenotype compared with those with tremor-dominant PD. Furthermore, a significant positive correlation was seen between Enterobacteriaceae concentration and severity of motor impairment in those with the PIGD phenotype. Scheperjans and colleagues employed several mechanisms that contribute to the validity of their findings. For example, subjects were matched by age and sex, and those living in the same household and thus with similar diets, were excluded. Possible confounders and biases were appropriately accounted for with statistical analyses, adding further reliability to their findings. As with any study of limited sample size, further research is needed to understand its external validity in relation to factors that have an impact in microbiota composition such as age, sex, diet, geographical