In this pilot study we investigated 10 women suffering from primary fibromyalgia. All patients received 5 mg of tropisetron in the evening, for a period of 4 weeks. Clinical disease variables included the measurement of a pain score, fatigue, sleep disturbances and measurement of the number of tender points. Five of our patients (50%) showed a statistical clinical improvement of all the above parameters starting after the first week of treatment. Two patients did not respond to the therapy and three discontinued the study because of side-effects. We conclude that administration of tropisetron in fibromyalgia patients could be useful in the management of this difficult and incurable syndrome.