In this study, we experienced a case of an elderly man with clinically undiagnosed squamous cell carcinoma of the lung, who died 8 days after a trauma. This case was autopsied because of a question over the causal association between the trauma and death. From the autopsy findings, it was judged that respiratory and metabolic abnormalities due to lung cancer were exacerbated by trauma, and that medically the cause of death should be assessed as death by disease.