The effectiveness of spa therapy in the management of patients with Parkinson's disease (PD) has never been evaluated. This is assessed in this pilot study. A prospective, randomized, cross-over, controlled study was conducted in 31 PD patients who underwent a 20-week spa period, including spa therapy for 3 weeks, and a 20-week non-spa period. Effectiveness was assessed using quality of life scales (PDQ-39 and SF-36), motor scale (UPDRS) and psychological questionnaire (GHQ-28), at baseline and at 4 (T4) and at 20 weeks (T20). Direct medical costs (radiological and laboratory tests, physician fees, drug therapy, and ancillary care) were recorded over each 20-week period. At T4, spa therapy improved significantly several dimensions of PDQ-39 and SF-36, part IV of the UPDRS, and GHQ-28. At T20, no difference in any parameter was found. The mean direct medical cost over 20 weeks (€1,328 ± 167; £776 ± 97 per patient) in the spa period was slightly but significantly reduced in comparison with that of the non-spa period (€1380 ± 523; £807 ± 306 per patient). This cost-effectiveness analysis suggests that spa therapy is more effective and less expensive than conventional treatment alone and could be beneficial in the management of PD.