Suicidal ideation is prevalent in patients with obsessive-compulsive disorder (OCD); but, during COVID-19 it may be increased . The present study aimed to examine the effects of obsessive-compulsive (OC) symptom dimensions and OCD severity on suicidal ideation by considering the role of stress responses in reaction to COVID-19 in a clinical sample of patients with OCD . In a cross-sectional study , 304 patients with OCD completed measures of OC symptom dimensions, OCD severity, general mental health (depression and anxiety), and COVID-19-related stress . Results showed that after controlling for depression, anxiety, comorbidity, and lifetime suicide attempts, the OC symptom dimensions of responsibility for harm and unacceptable obsessional thoughts as well as general severity had indirect effects on suicidal ideation through the specific stress responses to COVID-19, including traumatic stress and compulsive checking . The study shows that OCD patients with specific OC symptom dimensions and severe OCD are more likely to have suicidal ideation during the pandemic . Further, the specific stress responses to COVID-19 may be an underlying mechanism . Clinicians should carefully assess suicidal ideation in patients with OCD who experience responsibility for harm and unacceptable thoughts, particularly during the pandemic.