BACKGROUND: Functional dyspepsia (FD), belching disorders (BD) and functional heartburn (FH) are the three most common upper functional gastrointestinal disorders (FGID) in IBS patients. FD is known to exert deleterious effects on health-related quality of life (HRQoL) and the psychological status of IBS patients; however, the impact of overlapping BD and FH on anxiety, depression and HRQoL of IBS patients remains unknown. This cross-sectional study was conducted to investigate the impact of overlapping FD, BD and FH on anxiety, depression and HRQoL in patients with IBS. METHODS: This study enrolled 319 consecutive outpatients with IBS from 2 tertiary hospitals in Beijing and Shijiazhuang of China. IBS, FD, BD and FH were diagnosed using the Rome III Criteria. Hospital Anxiety and Depression Scale and a 36-item Short-Form Health Survey (SF-36) were used to assess the psychological distress and HRQoL of patients respectively. RESULTS: Among the 319 patients with IBS, the IBS subtypes were diarrhoea (67%), constipation (16%), unsubtyped (12%) and mixed (5%). These IBS patients were further classified into IBS + FD, IBS + BD/FH (BD and/or FH), IBS + FD + BD/FH, or IBS only according to the patients' overlapping upper GI symptoms. IBS+FD patients reported higher levels of anxiety than IBS+BD/FH and elevated depression scores than IBS only patients (P< 0.05). The latter observation remained consistent after confounder-adjustment. The IBS + FD and IBS + FD + BD/FH groups exhibited statistically significant impairment in most of SF-36 scales, while the IBS + BD/FH group only showed lower HRQoL results in general health, when compared to the IBS only group. Multiple linear regression analysis demonstrated IBS + FD + BD/FH was linked to worse mental, physical and global HRQoL. Furthermore, IBS + FD was a strong predictor of poorer physical and global HRQoL compared to IBS only. CONCLUSIONS: Among the diarrhoea-prevalent IBS patients, those with concomitant FD experienced more psychological distress and demonstrated poorer physical HRQoL. Overlapping FD + BD/FH is a significant predictor of worse mental and physical HRQoL for IBS patients. The impact of concomitant BD and FH on the psychological status and HRQoL of IBS patients was limited. These findings implied that the overlapping upper FGIDs in IBS might be treated distinctively when developing comprehensive management strategies for IBS treatment.