Balneotherapeutic applications to treat rheumatic diseases have a long-term tradition and are based on established scientific principles, and the majority of rheumatic diseases most frequently include balneotherapy. However, as other therapeutic strategies, balneological interventions require scientific proof of their effect and efficacy. Notably, recent studies providing evidence of the thermic and chemical effects on the immune system and cytokine milieu have enforced the revival of the traditional balneological interventions. This review provides an overview of the known as well as the novel aspects of balneotherapy and their clinical relevance in the treatment of rheumatic diseases.