Since ancient time, thermal baths and mudpacks have been used as treatments for rheumatic diseases and other musculoskeletal complaints. Despite basic researches suggest an anti-inflammatory effect of spa therapy, there is no consensus about the benefits of balneotherapy in patients with chronic inflammatory rheumatic diseases. The aim of this review is to summarize the currently available information on clinical effects of balneotherapy in these diseases. We did a literature search for articles considering the randomized controlled trials (RCTs) published until today. Although many selected studies do not have an elevated methodological quality, data from these RCTs support a beneficial effect of spa therapy. Balneotherapy highly improves the clinical course of the disease in patients with predominant axial involvement, such as with ankylosing and enteropathic spondylitis; the effects are less favorable in patients with predominant peripheral articular inflammation, such as rheumatoid arthritis. Good results have been observed in patients with psoriatic arthritis, but only few RCTs have been conducted on this disease. Spa therapy appears safe, and adverse events have been reported only in a few patients.