Editor,—Emergency departments in NSW have been collecting computerised data about the patients they see using the Emergency Department Information System since 1994.¹ It is possible to use these data to investigate the extent to which the availability of general practitioner services varies with the rate of primary care presentations to NSW emergency departments. It might be expected that emergency departments would see more primary care patients on weekdays that were public holidays than weekdays that were not, because general practices are usually closed on public holidays. In Australia primary care patients have been defined by the National Health Strategy as those …