Physical functional ability and nutritional status are two major indicators for predicting the risk of mortality in older adults. The present study examined the complementarity of the Activities of Daily Living (ADL) and the Mini-Nutritional Assessment (MNA) for predicting follow-up 4-year all-cause mortality risk in elderly Taiwanese. We analysed data of the ‘Survey of Health and Living Status of the Elderly in Taiwan’, a population-based longitudinal cohort study which involved 2872 men and women of ≥ 65 years old at baseline (1999). We rated their functional dependency with the ADL scale and nutritional status with the MNA (both the long form, LF and the short form, SF) at baseline, and analysed the complementarity of the two scales in predicting follow-up 4-year all-cause mortality with Cox regression analysis and the net reclassification improvement (NRI) to quantify the improvement. The results showed that both ADL and MNA offered improvement in predicting follow-up mortality risk beyond that predicted by either one alone according to the Akaike information criterion and the NRI. The MNA-SF was nearly as effective as the MNA-LF in improving the predictive ability of the ADL. The present study suggests that the MNA (especially the SF because of its simplicity and time-saving feature) together with the ADL scale might be of value for predicting the mortality risk of frail elderly living in various settings.