In this edition, Collins et al review evidence of gut microbiome-brain interactions in mice and focus on the ability to transfer behavioral traits between mouse strains using fecal microbiota transplantation (FMT). Transplantation alters brain chemistry and behavior in recipient ex-germ free mice, raising the possibility of using FMT for prevention and treatment of disorders of the central nervous system. Evidence in humans is currently lacking but future investigation of the intestinal microbiome in Central Nervous System (CNS) disorders seems warranted These recent findings imply that donors for FMT therapy in humans should exclude individuals with CNS and psychiatric illness.