The medical record form included in Spanish Royal Decree 396/2006 (Annex 5), regulating health protection for workers exposed to asbestos, is an important source of information on the health effects of asbestos exposure. The frequency and percentage of correctly filled data was assessed in a sample of 400 medical records. Overall, data completeness was low, especially regarding individual identification data, occupational history and results of radiographic studies. The poor completeness of recorded data hinders accurate knowledge of the impact and effects of asbestos on Spanish workers' health.