This is an autopsy report of multiple primary cancers observed in a patient who had clinically been diagnosed as chronic arsenic poisoning. An 88-year-old man, non-smoker, had worked in an arsenic mine for 6 years from the age of 47. He had undergone operations for Bowen's disease and gastric cancer at ages 80 and 86, respectively. At autopsy, squamous cell carcinoma of the lung and a polypoid lesion in the piriform recess were found. Furthermore, microscopic examination revealed latent prostatic adenocarcinoma and oncocytoma in the kidney. The polypoid lesion of the piriform recess appeared to originate from the duct of the minor salivary gland in the pharynx, showing an adenoid cystic carcinoma-like pattern with squamous cell carcinoma in part. The cause of death was thought to be respiratory failure due to bronchopneumonia and pulmonary edema as well as hydrothorax, and chronic heart failure following ischemic heart disease. Bowen's disease was followed by four internal malignant tumors, even though the etiological relation between these cancers and arsenic is not clear.