Since the establishment of the Portable Antiquities Scheme, the systematicreporting of metal-detected finds in England and Wales has increased ourknowledge of distribution patterns and complemented the evidence fromassemblages uncovered by conventional excavation. The large number of Romanmetal small finds documented, particularly brooches, now allows for aquantitative comparison between those recovered through excavation and thosediscovered by metal-detecting. This study shows that certain artefactmorphologies are more easily detected than others, resulting in differentialrates of representation in the archaeological record. It is suggested thatsimilar biases can be seen in artefacts from other periods. This hasimportant consequences for anyone wishing to use metal-detected material insynthetic studies.