Aim. This study investigated registered nurses' knowledge of documentation used in aged-care nursing home facilities in Queensland, Australia. Background. The purpose of nursing documentation is to communicate health information, facilitate quality assurance and research, demonstrate nurses' accountability and, within Australia, to support funding of residents' care. Little is known about the relationship between RNs' knowledge of nursing documentation, the documentation process within residential aged care and the outcomes of the documentation. Design. Cross-sectional, retrospective design. Method. The study was conducted with a large sample of RNs (n = 360) located in 162 Queensland aged-care facilities. Participants completed a postage-return questionnaire in which they identified factors that influence their knowledge and understanding of documentation. Results. Participants reported that they have considerable knowledge of nursing documentation. They also indicated that they were most knowledgeable about policies on documentation and writing discharge instructions. However, their knowledge of nursing assessments ranked fifth and they were least knowledgeable about reading reports each shift. Conclusions. The modified version of Edelstein's questionnaire provided a valid and reliable instrument for measuring RNs' knowledge of nursing documentation. A factor analysis of the 16 items in the Knowledge scale showed excellent reliability. The data indicated that RNs in aged-care facilities have high levels of knowledge about documentation. Specific recommendations relate to the implementation of comprehensive documentation education programs that reflect the needs of organisations and the level of RNs' skills and knowledge concerning documentation. Relevance to clinical practice. Accurate nursing documentation is relevant to residents' care outcomes and to government funding allocations. Measuring RNs' knowledge of nursing documentation can identify factors that impede and facilitate their documentation of care.