Key PointsQuestionIs diagnosing bipolar spectrum disorder in adolescents associated with suicide prevention?FindingsIn this cross-sectional study of 585 confirmed suicide deaths in Sweden, regional bipolar disorder diagnosis rates in adolescent males were associated with a lower suicide death rate at an estimated magnitude of approximately 4.7% of the national average. Independent of annual regional depression and schizophrenia diagnoses, lithium dispensation, and psychiatric care affiliation rates, results were consistent with previous reports suggesting that bipolar disorder is implicated in approximately 4.9% of unselected suicide deaths in young adulthood.MeaningThe findings indicate that diagnosis of bipolar disorder in male adolescents may be important for suicide prevention.