There are two basic types of bedpan systems in use, the non-disposable and the disposable. The disposable bedpan system uses two types of paper pulp liner. One is a disposable bedpan liner with a re-usable plastic support and the other is a totally disposable self-supporting unit. Although it has been said that the latter system is to be preferred (Gibson, 1974; Leading article, 1974) there are difficulties in the manufacture of self-supporting paper pulp bedpans. Those available for test were acceptable but disadvantages are extra cost, greater weight of paper pulp and an increased use of water. Nevertheless, a self-supporting disposable bedpan obviates the need to clean and disinfect plastic supports which may become offensive and present bacteriological hazards both to nurse and patient. With the disposable system, liners and their contents are macerated in a destructor and discharged directly into the sewage system. It follows that the drainage system has to be adequate before such disposal units are installed although this is also true of effluent from bedpan washer/disinfector systems. Previous examination of bedpan disposal machines showed several defects (Gibson, 1973a) and recent surveys of such systems (Hawkins, 1979; Collins, Deverill, Taylor & Oates, 1980) have emphasized the need for practical education in their use to overcome operational difficulties. Following earlier reports (Gibson, 1973a) manufacturers offered modified machines with improvements aimed at reducing the escape of aerosols to insignificant levels. Further tests on an improved disposal unit showed a satisfactory performance (Gibson, 19733). The aim of this study was to assess the bacteriological hazards from a modified ‘Clinimatic’ MK Vl (Tweedy of Burnley Ltd.) bedpan disposal machine, and its efficiency in routine use over a long period.