The plain abdominal X-rays of 277 patients suffering from five acute abdominal conditions were reviewed and specific radiological features found to occur in not less than 48% of the cases. In a second series of 249 patients admitted to hospital with an acute abdomen due to all types of disease, the plain abdominal X-rays were helpful in 42% of cases. A questionnaire of 50 plain abdominal X-rays was answered by surgeons and radiologists of varying clinical experience, the scores of the senior radiologists being higher. It is suggested that plain abdominal X-rays should become a routine investigation in the acute abdomen, and should be reported by senior radiologists at the time of the investigation.