An 86-year-old man was referred by his family physician to our clinic because of sudden onset aphonia immediately after a Japanese-style bath. On examination, the only abnormality was aphonia, with an otherwise normal physical examination. However, we found vocal fold oedema on laryngeal fibrescopy. For treatment, he was immediately given 30 mg prednisolone intravenously. Twelve hours after injection the oedema had completely disappeared and his aphonia had resolved. The patient was healthy for three months after returning home. However, at the beginning of a cold winter night he again complained of sudden onset hoarseness, after taking a Japanese-style bath. Japanese-style baths are completely different from Western-style baths. There is a temperature difference of almost 30 degrees C between the inside and outside of a bath; the transition may represent a type of physical exercise in elderly and exhausted individuals. This difference could cause a cold or heat-induced allergic reaction. We strongly recommend a laryngeal study in case of sudden onset aphonia.