OBJECTIVES: To assess the impact of measures undertaken to improve data capture in the Fabry Outcome Survey (FOS). A physician-directed, multinational database established in 2001, FOS aims to advance the understanding and management of Fabry disease, a rare lysosomal storage disorder caused by deficiency of alfa-galactosidase A.  METHODS: This initiative, supported by Shire HGT is driven by physicians in the management of Fabry disease. In 2006, additional measures were introduced to enhance the robustness of data capture: 1) a core dataset was developed for assessing disease progression and therapy response; 2) focus was directed at those participating centers with ≥20 patients enrolled in FOS; and 3) research associates were employed to monitor data capture and quality. Random samples (25%) of all enrolled patients were selected from the years 2004 and 2007, before and after the changes, respectively. The completeness of data capture was determined for 10 core variables in each year.   RESULTS: Data capture was analyzed for 197 of the 815 patients enrolled in FOS in 2004 and for 404 of the 1616 patients enrolled in 2007. Increases in data capture occurred for 9 of 10 core variables; the exception was patient weights, which were unchanged at 90% for both years. For key variables, the increases were: signs and symptoms, from 66% to 83%; serum creatinine, from 89% to 91%; left ventricular mass, from 48% to 55%; NHYA score, from 84% to 87%. In addition, the proportion of females enrolled increased from 48% to 54%.  CONCLUSIONS: Focused efforts on improving data completeness and quality in FOS have been successful, optimizing the value of the database. Regular, accurate data collection and audit will increase the quality of FOS data and lead to an improved understanding of the management of Fabry disease.