Very few studies tested the effectiveness of spa therapy in older patients with osteoarthritis. Therefore, we aimed to evaluate the short-term effects of spa therapy in patients aged 65 years and older with generalized, knee, hip, and cervical and lumbar spine osteoarthritis. In an observational retrospective study design at the Medical Ecology and Hydroclimatology Department of Istanbul Medical Faculty, we analyzed the records of 239 patients aged over 65 years with the diagnosis of all types of osteoarthritis who were prescribed a spa therapy course in some spa resorts in Turkey between 7 March 2002 and 31 December 2012. They travelled to a spa resort where they stayed at a thermal spa hotel and followed the usual therapy packages for 2 weeks. Patients were assessed by an experienced physician within a week before the spa journey and within a week after the completion of the spa therapy. Compared with baseline in whole sample, statistically significant improvements were observed in pain (visual analog scale, VAS), patient and physician global assessments (VAS), Health Assessment Questionnaire disability index (HAQ-DI), Lequesne algofunctional index (LAFI) for knee, Western Ontario and McMaster Universities index (WOMAC), Waddell disability index (WDI), and Neck Pain and Disability Scale (NPAD). According to Outcome Measures in Rheumatology-Osteoarthritis Research Society International (OMERACT-OARSI) Set of Responder Criteria, responder rate were 63.8 % (51/80) in generalized, 52 % (13/25) in knee, 50 % (2/4) in hip, 66.7 % (8/12) in lumbar, and 100 % (6/6) in cervical osteoarthritis subgroups. Spa therapy improved pain and physical functional status in older patients with osteoarthritis, especially generalized osteoarthritis and multiple joint osteoarthritis with involvement of knee. This improvement was clinically important in majority of the patients. To confirm the results of this preliminary study, there is a need of a randomized controlled clinical study comparing spa therapy with usual care in the elderly population with osteoarthritis.