The degree of substance-induced syndrome (SIS) was evaluated in 5,116 acutely hospitalized suicidal psychiatric inpatients. Admission and discharge severity ratings were made by academic attendings using structured forms. Outcome variables analyzed include ratings of psychiatric symptom severity on admission and discharge, length of stay, severity of SIS, and severity of alcohol/drug problems. Suicidal inpatients rated with a high degree of SIS were more likely to be homeless, to be unemployed, to be uncooperative, to have shorter lengths of stay, and to show a more rapid improvement in symptoms. These patients represent a subgroup of the co-occurring disorders population having a high degree of addiction severity with temporary substance-induced suicidal syndromes and are subjected to the most expensive level of care in the mental health system. Implications of these findings include the fact that psychiatric inpatient services need to provide intensive addiction intervention treatment and that outpatient addiction services need improved capability and capacity to care for suicidal patients. (Authors)