Background Suicide rates are around three times higher in men than women; in contrast women have a higher prevalence of community-diagnosed depression. To investigate this paradox we examined the association of General Health Questionnaire (GHQ)-caseness (score 4), a measure of possible minor mental disorder, with suicide risk in a general population cohort. Methods Data were derived from a cohort study based on the 8,466 men and women in the Renfrew and Paisley cohort who completed a 30-item GHQ in the period from 1972 to 1976 and who were followed up to 1995 for all-cause and suicide mortality. Results The long-term suicide risk associated with possible minor mental disorder was higher in men [hazard ratio 6.78 (1.36-33.71)] than women [hazard ratio 1.66 (0.43-6.45)]; test for interaction between gender and GHQ with respect to suicide risk: p = 0.09. Conclusion These findings indicate either that the long-term risk of suicide in the context of a past episode of minor mental disorder is higher in males than females or that there are sex differences in the validity of responses to mental health screening questionnaires. Further research is required to replicate our finding in larger studies and, if confirmed, clarify which explanation underlies it.