Abstract: Objective To investigate severity of gastrointestinal symptoms, quality of life, and mental health status of patients with irritable bowel syndrome (IBS) and functional dyspepsia (FD). Methods IBS patients were enrolled consecutively at the Outpatient Department of Gastroenterology, West China Hospital, Sichuan University from September 2012 to May 2013. The participants were divided into two groups according to their appearance with FD. Ten healthy volunteers served as normal controls. A questionnaire survey was undertaken to measure scores of gastrointestinal symptom rating scale (GSRS), Chinese IBS-quality of life (ChIBS-QOL), Hamilton Anxiety Scale (HAMA), Hamilton Depression Scale (HAMD) and medical conditions. Results Twenty-five (41.7%) IBS patients were overlapped with FD (IBS-FD). The IBS-FD patients had significantly higher scores of GSRS than IBS patients and healthy volunteers (P<0.05). The IBS-FD patients saw doctors more frequently than IBS patients (P<0.05). Neither anxiety nor depression were observed in healthy volunteers. The IBS patients were more likely to present mild anxiety and depression, while the IBS-FD patients were more likely to present moderate to severe anxiety and depression. The IBS-FD patients had significantly higher prevalence of anxiety and depression than IBS patients (80.0% vs. 51.4%, 76.0% vs. 48.6% respectively, P<0.05). Scores of GSRS, ChIBS-QOL and prevalence of anxiety and depression were the highest in the IBS-FD patients with constipation (IBS-C-FD, P<0.05). Conclusion IBS-FD patients especially those with constipation suffer more gastrointestinal discomforts, and are more likely to suffer from anxiety and depression and poor quality of life compared with those with IBS only.