Diffuse medical waste is at the centre of much vigorous discussion. Despite the evolution in the perception of waste-related dangers over the ages and with changes in usage, the association of risk with diffuse medical waste in particular continues to be widespread. There are two dimensions to the risk in question: objective and its corollary, perceived dimension, both of which are in need of appraisal. The RI/FS method lent itself to the appraisal of objective risk, whereas the risk as perceived by independent health practitioners in Greater Lyon was assessed by means of a survey. The results of this survey were compared against the results of a study on the objective risk presented by these types of waste in relation to similar risks presented by household refuse. It emerged that practitionners overestimate the objective risk, and this difference enables the measure of perceived risk to be gauged. Several scenarios may be put forward for diffuse medical waste management on the basis of these results.