In an earlier publication that investigated alexithymia in fibromyalgia, we showed the Toronto Alexithymia Scale was the only instrument being used to measure alexithymia.To find out which instruments are currently available for measuring alexithymia, to compare the psychometric properties of these instruments and to decide whether some of the test methods involved should be used to give extra value to alexithymia research.We conducted a systematic review of the literature in Medline/PubMed with a number of search terms. We selected articles relating to psychometric properties of the tests performed and decided whether they could be influenced by negative affect.We found that 14 different instruments were used to measure alexithymia. From our evaluation we excluded tests which had weak psychometric properties or had been inadequately assessed. There remained three observation scales and two self-report questionnaires, which had been adequately validated and whose relative strengths and weaknesses were compared.In view of these findings, we recommend that in studies of alexithymia in fibromyalgia a multimodal measurement method should be used rather than only the tas-20.