Stigmas surrounding mental illness in the criminal justice system often influence jurors' decisions, sometimes aggravating (increasing) and sometimes mitigating (decreasing) sentencing decisions. Jurors' own personal experiences with mental illness could be an underlying factor in sentencing a defendant. However, personal experiences of jurors still require much research to understand individual characteristics and environmental influences in their decision making. Thus, the purpose of the present study was to investigate how mental illness symptomology may influence perceived responsibility proposed sentencing of a criminal defendant. 214 participants read a fact pattern from a Supreme Court opinion involving homicide and rated the guilt and proposed sentencing of the defendant (who either received a diagnosis of bipolar disorder, whose symptoms were described, or no mental illness was involved). Participants also completed the Brief Symptom Inventory. Results indicated that there was no interaction between mental illness of the defendant and juror sentencing decisions; however, there was an interaction between juror symptomology and recommended sentence length of the defendant in years. Personal symptomology of jurors' is a predictor of recommended sentence length of a defendant, in years (p < .05). Implications for future research and for practical applications are discussed.