BACKGROUND: Gastroesophageal reflux disease (GERD), functional dyspepsia (FD) and irritable bowel syndrome (IBS) are common functional gastrointestinal conditions with a significant impact on daily life. The objectives were to analyse general self-rated health and self-reported functional capacity in adults meeting the criteria for GERD, FD and IBS, respectively, and in individuals who meet the criteria for more than one of the conditions. METHODS: A nationwide study of 100,000 individuals aged 20 years and above, randomly selected in the general Danish population. A web-based questionnaire survey formed the basis of this study. Questions regarding FD and IBS were extracted from the ROME III adult questionnaire. Questions regarding GERD were developed based on the Montreal definition. Self-rated health and functional capacity was measured by single global questions. RESULTS: Respondents meeting the criteria for either GERD, FD or IBS have significantly higher odds of reporting poor self-rated health and impaired functional capacity compared to individuals not experiencing these functional gastrointestinal conditions. Furthermore, respondents with overlapping gastrointestinal (GI) symptom complexes have significantly higher odds of reporting poor self-rated health and impaired functional capacity compared to respondents with symptoms compatible with only one of the symptom complexes. CONCLUSIONS: This study demonstrates that individuals experiencing symptoms of GERD, FD or IBS report poor self-rated health as well as impaired functional capacity. The impact on self-rated health and functional capacity is highest among individuals experiencing overlapping symptoms of GERD, FD and IBS.