Balneotherapy and spa therapy emerged as an important treatment modality in the 1800s, first in Europe and then in the United States. Balneotherapy involves immersion of the patient in mineral water baths or pools. Today, water therapy is being practiced in many countries. Examples of unique and special places for balneotherapy are the Dead Sea in Israel, the Kangal hot spring in Turkey, and the Blue Lagoon in Iceland. Bathing in water with a high salt concentration is safe, effective, and pleasant for healing and recovery. This approach needs no chemicals or potentially harmful drugs. There are almost no side effects during and after treatment, and there is a very low risk to the patient's general health and well-being. Mineral waters and muds are commonly used for the treatment of various dermatologic conditions. The major dermatologic diseases that are frequently treated by balneotherapy with a high rate of success are psoriasis and atopic dermatitis. The mechanisms by which broad spectrums of diseases are alleviated by spa therapy have not been fully elucidated. They probably incorporate chemical, thermal, mechanical, and immunomodulatory effects. The major importance of balneotherapy and spa therapy both individually and as complements to other therapies lies in their potential effectiveness after standard medical treatments have failed to give comfort to these patients.