Abstract: INTRODUCTION: Many patients at risk for suicide present in primary care where insomnia and other suicide risk factors are prevalent. Addressing insomnia in this milieu may augment suicide prevention strategies. METHODS: A randomized clinical trial was conducted to test the effectiveness of brief cognitive behavioral therapy for insomnia (bCBTi) for primary care patients at risk for suicide recruited from three U.S. Veterans Health Administration practices. The 194 participants (77% male; mean age 51.5+/-13.6 years) with insomnia, co-occurring depression and/or posttraumatic stress disorder (PTSD) and recent death or suicide ideation were randomized to receive four 30-minute sessions of bCBTi or Sleep Hygiene over six weeks. Blinded assessments occurred every 6 weeks from baseline to 30 weeks. Change in Insomnia Severity Index (ISI) across 30 weeks was the primary outcome with co-secondary outcomes measured by the Scale for Suicidal Ideation (SSI), Patient Health Questionnaire-9 (PHQ-9) and PTSD Checklist (PCL). RESULTS: Mixed level modeling showed a significant condition effect at posttreatment (6-weeks) for ISI favoring bCBTi (t(df) = -4.58(153); p < .0001) which was maintained through 30-weeks (t(df) = 0.35(141); p >.05). PHQ-9 was lower at 6 weeks in the bCBTi condition (t(df) = -2.07(155); p = .04) maintained through 30 weeks (t(df) = -0.47(137); p > .05). No PCL differences and no difference in SSI at posttreatment. However, a significant timexcondition effect from 6 to 30 weeks existed for SSI favoring bCBTi (t(df) = -2.60(118); p = 0.01). CONCLUSION: The bCBTi intervention designed for primary care settings effectively reduces insomnia severity with modest effects for depression and suicidal thoughts, offering an adjuvant to suicide prevention strategies.