BACKGROUND The attachment theory aims to understand close relationships in adulthood based on the relationship of a child with the caregiver. Attachment styles are classified as secure, preoccupied, fearful and dismissing, which are the subtypes of insecure attachment style. Insecure attachment is suggested to be related to depression and suicide. In this study, the relationship of suicidal ideation and behavior to attachment style is investigated in patients diagnosed with major depression. METHODS Sixty-two patients diagnosed with major depressive disorder according to the DSM-IV-TR criteria were taken and divided into two groups, 31 patients with and 31 patients without a past suicide attempt. Sixty healthy volunteers matched with the patients for age, gender and education and comprised the control group. Sociodemographic and clinical data form, Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), Hamilton Depression Rating Scale (HDRS), Experiences in Close Relationships Scale (ECR), Scale of Suicidal Ideation and Suicidal Behavior Scale were applied to the groups. RESULTS In the patients with depression, ECR anxiety and avoidance scores were found to be higher compared with those in the control group. There were no differences in the anxiety and avoidance scores between the patients with and without suicide attempt. The rate of participants who showed secure attachment style in the control group was higher than that of those with depression. In the patients with fearful attachment style, the suicide attempt rate was found to be higher than the other groups. A positively significant relationship was detected between ECR anxiety score and scores of HDRS suicide item, Scale of Suicidal Ideation and Suicidal Behavior Scale. CONCLUSIONS Patients with depression were more anxious and more avoidant and showed more insecure attachment. In patients with depression with fearful attachment style, suicide attempts were more common.