Two hundred and fifty-nine men and women aged 20-45 years who did not respond to an offer from their general practitioner for a health check were interviewed at home to explore the reasons for non-response. There was no support for the view that the invitation aroused anxiety or that the administrative arrangements had been a barrier to acceptance. Many subjects were not really interested (44%) or just forgot to attend (24%). Crises at work or home (26%) and current attendance at a doctor (16%) were other reasons offered, while 11% felt screening to be in appropriate. There is little that can be done to change these rates except by a shift of public opinion to more consumer demand for health checks or by more opportunistic health checks when people attend their doctors for other reasons. The dangers of marketing health checks to increase consumer demand are discussed in the light of these findings and other work.