The development of the spa resort began in 1923, when the state took over its care. Dr. Đoka Mihajlović was appointed as the spa doctor in 1926 and sent to Czechoslovakia in 1928 to specialize in balneophysical therapy for internal diseases. In 1935, the New Bath (now known as the „Old Bath”) was built, which allowed for more visitors. Between 1935 and 1940, the spa experienced its peak period, with an average of over 6,000 guests. There were 510 beds in catering and 530 beds in private accommodation, with one permanent and four seasonal doctors. By 1950, the spa resort had four hotels and two villas, with a total of 570 beds. However, it was noted that the accommodation capacities were insufficient, even with 800 beds in private accommodation. Contracts were made between the republican and municipal social insurance institutes and the catering company „Niška Banja” for the accommodation of patients. The spa resort only provided health services.