It is a common Japanese custom to enjoy a hot bath daily and it is also well known that hot bathing has been associated with sudden death, especially in elders. Approximately 13% of the sudden death cases in Japan occur during bathing. This number has been increasing with the aging of Japan’s population. One of the causes lies in the Japanese bathing style, in which the bath consists of a tub deep enough for the bather to immerse the body up to the neck in very hot water when sitting, and in the fact that the temperature of bathrooms is quite low in winter season. Therefore, it is an urgent problem to study the physiological effects of hot bathing and to educate Japanese people on its safe ways. This article reviews the variable effects of hot bath immersion on human bodies in order to introduce the safe way of hot bathing. Yet the definite causes of those deaths have not been fully understood. Thus, we investigated the effects of bathing on the elderly, especially regarding cardiopulmonary functions. We studied 12 apparently healthy elderly volunteers (70±5yr). They bathed in different temperatures (41。C, 38。C) on separate days. In the 38。C bath immersion, none of the cardiopulmonary indices changed significantly. In contrast, the 41 。C bath immersion significantly increased BR, PRP, and Ttymp, suggesting a higher bathing temperature may give more stress to the cardiopulmonary system. Bathing in hot water affected elderly people with underlying diseases much more than healthy or younger people.