BACKGROUND: A family history of completed suicide and psychiatric illness has been identified as risk factors for suicide. AIMS: To examine the risk of offspring suicide in relation to parental history of suicide and other parental risk factors. METHOD: The study population consisted of 7,177 adult offspring born 1959-1961 and their parents from the Copenhagen Perinatal Cohort. Cohort members and their parents who had committed suicide were identified in the Danish Causes of Death Registry (follow-up until December 31, 2005), while information on psychiatric hospitalisation history was obtained from the Danish Psychiatric Central Research Register. RESULTS: Forty-eight cohort members, 77 mothers and 133 fathers had committed suicide during the follow-up. Independent of parental psychiatric illness and social status, parental suicide significantly increased suicide risk in offspring (hazard ratio 4.40 with 95% CI 1.81-10.69). A stronger effect of parental suicide was observed in offspring without a history of psychiatric hospitalisation. CONCLUSION: Parental history of suicide is a risk factor for suicide in offspring, but primarily in offspring without psychiatric hospitalisation.