A method and apparatus for estimating a respiratory rate of a patient. The method comprises the steps of recording respiratory sounds of the patient, deriving a plurality of respiratory rates from the recorded sounds using a plurality of respiratory rate estimating methods and applying a heuristic to the plurality of derived respiratory rates, the heuristic selecting one of the derived respiratory rates. The selected respiratory rate is the estimated respiratory rate. The apparatus comprises at least one sensor recording respiratory sounds of the patient, a plurality of respiratory rate processors, each of the processors comprising a respiratory rate calculating method, a heuristic means for selecting one of the calculated respiratory rates and a display means for displaying the selected respiratory as the estimated respiratory rate.