A study was undertaken to test the hypothesis that consultants who are willing to participate in expert panels are similar, in terms of routinely available characteristics, to those who are not participating. All consultants in acute specialties in North-east Thames Region were asked to participate in a series of expert panels. Routinely available data was used to compare those who agreed to participate with those who declined or did not reply. Consultants who are willing to participate in expert panels are similar to those who are not in terms of years since qualification, specialty, sex, country of graduation, and possession of higher degrees. Consultants working in district general hospitals seem to be more likely to be willing to participate than those employed in teaching hospitals (37% versus 26%, p less than 0.02), although this difference may be accounted for by errors in the list of teaching hospital consultants.