Riders of powered two-wheeled vehicles injured whilst riding their machines were interviewed either at hospital or at home in order to supplement data already held from police records. Of those 70 casualties interviewed, 49 (70%) were not known to the police via their Stats 19 records. Of these 49, 17 (35%) were classified as serious in accordance with Department of Transport criteria. The paper considers the management implications and methodological requirements needed to cope with under-reporting and obtaining supplementary data within an operational setting.