BACKGROUND: We previously demonstrated that the PDS gene is involved in the genetic susceptibility to autoimmune thyroid diseases (AITD) in Tunisia. In the same population, we now investigated the presence of anti-pendrin auto-antibodies (aAbs) in AITD patients' sera. METHODS: Thirty seven Tunisian AITD patients and 19 healthy subjects from families previously linked to the PDS gene, 75 unrelated patients and 20 healthy unrelated subjects were included in our study. The detection of anti-pendrin aAbs in patients' sera was performed by ELISA using membrane protein extracts of CHO cells expressing pendrin (CHO-hPDS) and by immunofluorescence using transient COS-7 cells expressing a GFP tagged pendrin. CHO cells transfected with human TPO in the same ELISA conditions were used as positive control. RESULTS: The majority of AITD patients' sera were positive for the presence of anti-TPO aAbs. In contrast, no reactivity was detected with CHO-hPDS membrane protein extracts. Likewise, no significant immunostaining was found on transfected COS-7cells upon exposure to patients' and controls' sera. CONCLUSIONS: Our data point to the absence of anti-pendrin aAbs in Tunisian AITD patients' sera.