The importance of the gut microbiome in health and disease is a rapidly growing area of research. Small intestinal bacterial overgrowth (SIBO) is a condition in which bacteria that typically exists only in the colon becomes concentrated in the small intestine. SIBO has wide-ranging clinical implications and the aim of this study was to review the current research to assess existing links between SIBO and various diseases. Examining the current literature, the authors found SIBO may be involved in several diseases. SIBO was found to be strongly associated with irritable bowel syndrome (IBS). While the link between SIBO and celiac disease has been studied extensively, findings remain inconsistent. Additionally, SIBO was found to be a potential underlying factor in hepatic encephalopathy. Based on these findings, the authors conclude the scientific hypotheses and the clinical findings are not consistent. While it is widely accepted that alterations in the gut microbiota can influence disease, there is not enough clinical evidence to draw conclusions. The authors conclude the evidence is promising but future research is needed.