Over the centuries, the complex balneological treatments used in Hévíz have been developed as a unique kind of medical care. The curative effect of the lake was probably known to the ancient Romans. Coins found in the lake in the early 1980s support this supposition. Discoveries from the age of Migration suggest that the migrant German and Slavic population used the lake as well. Written sources more than 400 years old come from the age of the Turkish invasion. In the mid 18th century, the Festetics family realized the curative effect of the lake and started its development as a spa. The lake and its surroundings became the family's property in the middle of the 18th century. As a start, Earl György Festetics I built a thermal wooden bathing house on a float over the outflow. After the earl's death in 1819 the development of Hévíz stopped. In 1868, György Festetics II purchased the building sites west of the lake and the building project of the bathing resort began. The bath houses looked more or less as they do today. In 1866 the mirrorbath was built. 

In 1905 Reischl Vencel, a brewery owner from Keszthely, became the tenant of the bath. It was then that Hévíz spa experienced an overnight success and became famous all over the country. Reischl built comfortable, modern hotels, restaurants and new bathing buildings. The unique entrance of the bath was finished in 1911 along with the Zander Institution. The unchecked boggy bush was cleared to allow for the growth of the newly planted park. The number of visitors increased exponentially. In 1911 Dr. Vilmos Schulhof founded the Zander and Röntgen Institution to meet the need for modern physiotherapy. It used gymnastics, powertherapy for treatment and X-ray apparatus for diagnosis. Dr. Odon Schulhof was invited to Hévíz from Budapest to work as a specialist in X-ray diagnosis and physiotherapy for the Zander. The Schulhof brothers in close cooperation with Dr. Karoly Moll were the ones who created the base for this very systematic development of the spa which made it suitable to serve the goals of the Hungarian Health Care System. Dr. Moll was the first person in the world to use subaqualis tractio. World War I stopped the development of the spa, but the growth continued again after 1923. Between 1944 and 1946 the bathing buildings were used as a hospital first by the German then by the Soviet army. In 1948 came a period of state ownership of the spa. The State Medicinal Bath, Hévíz (today St. Andrew's State Hospital for Rheumatology and Rehabilitation) was established by the Ministry of Health on 1 January 1952. The number of visitors doubled then quadrupled. By 1968 it has become Hungary's most modern winter bathing spa. In September 1989 the new set of buildings was made more attractive and up to date than the previous one. Today the area of the Institution is 620,000 square meters. The sophisticated balneotherapy complex of Hévíz and the spa are part of the world's cultural heritage.