The aim of this study was to evaluate the contribution of individual spa therapies administered during a period of 3 weeks on measures of well-being and pain in a sample of patients with chronic back pain. A total of 153 patients with chronic back pain undergoing inpatient spa therapy participated in the study. According to the prescription of their physician, patients underwent two or more of the following treatments: mud packs, carbon dioxide baths, massages, exercise therapies, spinal traction and electrotherapy. The outcome measures were general pain, back pain, negative mood and health satisfaction. Regression analyses were conducted to predict the four outcome measures at the end of spa therapy and at 6 weeks’ follow-up for all therapies applied. The pretreatment outcome measure, age and sex were controlled for by entering them into the analysis. Patients showed significant improvements in all four outcome measures. The prediction of improvement was generally small: only 1–11% of the change of the outcome measures could be explained by the type and number of therapies received. On a short-term basis, mudpacks and exercise were found to be associated with a greater improvement in mood, whereas a greater frequency of massage therapy and carbon dioxide baths was associated with a smaller improvement in health satisfaction. On a long-term basis, exercise therapy and spinal traction were associated with a greater reduction in back pain.