In a cross-over study, the short-term efficacy of whole-body cold therapy and hot mud packs in patients with generalized tendomyopathy (fibromyalgia) was compared. As a pain assessment, visual analog scale and so-called pain score were measured; dolorimetry of the 24 tender points and eight control points was performed as well. Using these methods, we found that there is a significant improvement of all parameters examined during a 2-h period of measurements after cold application, and a marked improvement was also detectable 24 h after this therapy. In contrast, only pain score values showed a slight decrease immediately after hot mud-pack therapy, and no significant differences were found in visual analog scale and pressure tenderness as measured dolorimetrically. Central inhibition of nociceptors as a result of an activation of A-delta system as well as a blockade of gamma-motoneurons are discussed to be a mechanism of action of whole-body cold therapy, resulting in a decrease in muscle tonus. Long-term studies are needed to determine, if there is any enduring effect of whole-body cold therapy on pain in the patients with generalized tendomyopathy.