Background/Aims: While depression severity is generally accepted as a risk factor for suicidal ideation, suicidal ideation in the elderly is sometimes thought to be unrelated to depression. This study examines whether depression severity predicts suicidal ideation across age groups and degrees of medical comorbidity. Methods: Electronic medical records from four large integrated health systems were used to examine outpatient Patient Health Questionnaire for depression scores (PHQ-9; used to determine depression severity). Patients 18 and older completed 1,117,072 PHQ9s between 2007 and 2011 and had data available to calculate Charlson Comorbidity Index scores (used to determine medical comorbidity). Suicidal ideation was measured via item 9 on the PHQ-9, which asked about thoughts of suicide. Results: Patients who had at least moderately severe depression were 50- to 100-times more likely to report considering suicide “nearly every day” than those with minimal or mild symptoms of depression. This relationship held regardless of age or degree of medical comorbidity, and regardless of whether someone had been diagnosed or treated for depression in the past. Discussion: The relationship between depression severity and suicidal ideation is robust and remains so regardless of age or medical comorbidity. Thoughts of death or suicide are not a natural or inevitable consequence of aging or chronic illness; patients of any age or medical comorbidity who have suicidal ideation should be screened for depression.