OBJECTIVE: Mitigation of suicide risk by reducing access to lethal means, such as firearms and potentially lethal medications, is a highly recommended practice. To better understand groups of patients at risk of suicide in medical settings, the authors compared demographic and clinical risk factors between patients who died by suicide by using firearms or other means with matched patients who did not die by suicide (control group). METHODS: In a case-control study in 2016 from eight health care systems within the Mental Health Research Network, 2,674 suicide cases from 2010-2013 were matched to a control group (N=267,400). The association between suicide by firearm or other means and medical record information on demographic characteristics, general medical disorders, and mental disorders was assessed. RESULTS: The odds of having a mental disorder were higher among cases of suicide involving a method other than a firearm. Fourteen general medical disorders were associated with statistically significant (p<.001) greater odds of suicide by firearm, including traumatic brain injury (TBI) (odds ratio [OR]=23.53), epilepsy (OR=3.17), psychogenic pain (OR=2.82), migraine (OR=2.35), and stroke (OR=2.20). Fifteen general medical disorders were associated with statistically significant (p<.001) greater odds of suicide by other means, with particularly high odds for TBI (OR=7.74), epilepsy (OR=3.28), HIV/AIDS (OR=6.03), and migraine (OR=3.17). CONCLUSIONS: Medical providers should consider targeting suicide risk screening for patients with any mental disorder, TBI, epilepsy, HIV, psychogenic pain, stroke, and migraine. When suicide risk is detected, counseling on reducing access to lethal means should include both firearms and other means for at-risk groups.