This study examined the prevalence and risk of psychiatric disturbances and suicidal behaviours among the peers of suicide attempters and completers. The subjects were selected from high schools with and without history of student suicides in the past 3 years. The psychiatric disturbances (as measured by the YSR and CBCL), suicidal behaviours, drug use, and a wide range of potential risk factors were measured. About a quarter of the peers of suicide completers and attempters were probable psychiatric cases and 15-21% of them reported suicidal acts. The increased risk of psychiatric disturbances and suicidal behaviours were still evident after controlling for age, sex, and potential risk factors. The presence of psychiatric disturbances could not wholly account for the increased odds of suicidal behaviours. Peers of suicide attempters carried a higher risk than peers of suicide completers. The close friends of suicide completers were particularly at risk of internalising problems, whereas the close friends of suicide attempters were at high risk of externalising problems. The peers of suicide completers and attempters represent a high-risk group for psychiatric disturbances and suicidal behaviours. The specific association of different types of psychiatric disturbances in the peers of suicide completers and attempters suggested that different risk mechanisms might be in operation within these peer groups.