To estimate changes in sexual behaviour over time. To examine the proportion of undiagnosed HIV infection in a community sample of homosexual men. To explore the relation between HIV status, diagnosis, and sexual behaviour.
Department of Primary Care and Population Sciences, Royal Free and University College Medical School, Mortimer Market Centre, Mortimer Market, off Capper Street, London WC1E 6AU, UK. jdodds@gum.ucl.ac.uk
