The aim of this study was to investigate the interrater reliability of the recognition of medically unexplained symptoms by medical investigators. The casenotes of 56 consecutive secondary care out-patient attenders were examined by three medical investigators. The investigators determined whether the presenting symptoms were medically unexplained (not, probable, or definite) and the results were tested for interrater reliability. The combined kappa for the three investigators was 0.76, indicating substantial agreement. This suggests that casenote examination is a reliable method of determining whether a symptom is medically unexplained.