BACKGROUND: The increase in longevity along with a high prevalence of chronic conditions contribute to increased disability burden. Despite the high occurrence of multimorbidity observed in advanced ages, most studies are restricted to the investigation of individual diseases. In this study, we assessed the impact of chronic conditions and multimorbidity on the disability burden in the older population in Belgium. METHODS: Data from 9,482 participants in the 2001, 2004, or 2008 Belgian Health Interview Surveys aged 55 years or older were analyzed. Disability was defined based on the Global Activity Limitation Indicator (GALI). To attribute disability to single chronic conditions and disease pairs, a multiple additive hazard model was fitted. RESULTS: Musculoskeletal conditions (45.3%), chronic respiratory diseases (11.2%), and cardiovascular diseases (10.2%) diseases were the most frequent conditions. Cardiovascular diseases, the co-occurrence of chronic respiratory diseases and depression, neurological diseases, cancer, and the combination of diabetes and cardiovascular diseases were the top five disabling conditions. The disability prevalence in the older population in Belgium was 35.6% (confidence interval =35.0; 36.2%). The most important contributors to the disability burden were musculoskeletal, cardiovascular, and chronic respiratory diseases. CONCLUSIONS: The present findings provide a deeper understanding of the role of chronic conditions and multimorbidity on the disability burden in the older population in Belgium. Although the disease pairs showed a low contribution to the disability burden, their occurrence presented a high impact on disability. Prevention strategies to tackle disability should target the main contributors to the disability burden and the most disabling conditions/disease pairs, especially in the clinical practice.