Objectives. The aim of the present study was to determine whether an aggregate simple clinical score (SCS) has a role in predicting the imminent mortality and in-hospital length of stay (LOS) of newly admitted, acutely unwell General Medical in-patients. Methods. Data were collected prospectively from adult patients admitted through an Acute Medical Unit between February and August 2013. Using logistic regression analysis before and after adjustment for age, the SCS was assessed for its association with LOS and mortality, including 30-day mortality, just for those patients for full resuscitation. Changes in sensitivity and specificity after adding SCS to age as a predictor, as well as the change in the net reclassification index, were determined using the predicted probabilities from the logistic regression models. Results. The SCS was superior to age in predicting mortality of any patient within 30 days. It did not assist in predicting 30-day mortality for those patients who were for full resuscitation. The ability of the SCS to predict long stay (>72h) remained relatively low (64%) and was inferior to published rates achieved by bedside clinician assessment (74%-82%). Conclusion. There was no useful prospective role for the SCS in predicting LOS and mortality of in-patients newly admitted to a General Medicine service. What is known about the topic? After their presentation to the emergency department, care efficiency is improved by the 'streaming' of patients according to their risk of imminent deterioration and their likelihood of being a long-stay patient. Although streaming is currently effected by bedside assessment of the patient, an accepted aggregate assessment score may assist disposition decisions. What does this paper add? Bedside assessment of each patient still offers the most accurate method for identifying the long-stay patient. The SCS, good at predicting 30-day mortality of all new admissions, is not useful for predicting the death of those admissions who are for full resuscitation. What are the implications for practitioners? When deciding admitted patients' disposition on leaving the emergency department, a simple aggregate score based on patient physiology, comorbidity and functionality has little to offer practitioners beyond knowledge of each patient's age.