The prevalence and severity of suicidal ideation was established in a patient sample seeking emergency treatment for non-psychiatric reasons. Using a computerised mental health screening panel, data were collected from waiting-room patients during randomised shifts over a 45-day period. Of 1590 screened patients, 185 (11.6%) acknowledged suicidal ideation and 31 (2%) reported planning to kill themselves. Almost all of those with suicidal ideation (97%) acknowledged symptoms consistent with mood, anxiety and/or substance-related disorders. Structured medical record review revealed that 25 of the 31 patients planning suicide were undetected during their index visit, and that 4 attempted suicide within 45 days of the visit. All survived.