Background: While numerous past reviews of psychological autopsy (PA) studies have examined the relationship between mental disorder and suicide, there has been little systematic investigation of suicide occurring in the absence of any identifiable psychiatric condition.

Aim: This article reviews available literature on the topic by considering Axis I, sub-threshold, mild disorders and personality disorders.

Method: We conducted a systematic review of PA studies from 2000 onwards. Studies included in the review had to clearly describe the proportion of suicide cases without a classifiable mental disorder or sub-threshold condition.

Results: Up to 66.7% of suicide cases remained without diagnosis in those studies that only examined Axis I disorders (n = 14). Approximately 37.1% of suicide cases had no psychiatric condition in research papers that assessed personality and Axis I disorders (n = 9), and 37% of suicides had no Axis I, sub-threshold/mild conditions (n = 6). In general, areas in China and India had a higher proportion of suicides without a diagnosis than studies based in Europe, North America or Canada.

Conclusion: Variation in the proportion of suicide cases without a psychiatric condition may reflect cultural specificities in the conceptualization and diagnosis of mental disorder, as well as methodological and design-related differences between studies.