The objective of this study was to evaluate the relative efficacy and tolerability of subcutaneously (s.c.) administered salmon calcitonin (sCT) in the treatment of patients with fibromyalgia. Eleven patients who fulfilled the American College of Rheumatology classification criteria for fibromyalgia were studied in a double-blind, crossover trial in which they alternatively received salmon calcitonin (100 IU s.c.) and isotonic saline (1 cc s.c.) for four weeks, with a four weeks wash-out period between the treatments. None of the 11 outcomes measures (seven analog scales, dolorimetry score, and three SIP scores) showed a significant improvement with sCT. The principal side effect observed with sCT was nausea in ten patients and erythema in four patients. These data suggest that sCT given at a dose of 100 IU daily for one month is not effective in the treatment of fibromyalgia.