therapy were screened. One patient (0.2%) tested positive for HBV and did not report any risk factor. As shown in Table 1, 22 patients (4.0%) tested positive on QFT and were classified as LTBI patients. Of these, 14 did not report any risk factor; 18 had always lived in The Netherlands; and another 18 never travelled outside of Europe, North America, or Australia. Further, 4 patients had abnormalities on chest X-ray; 3 of them also tested positive on QFT; and the other 1 turned out to have sarcoidosis, not LTBI. All LTBI patients were treated with isoniazid therapy. After a mean follow-up period of 19.8 ± 8.8 months, none of the patients had a reactivation of LTBI after the start of biological therapy. Conclusions: The overall prevalence of LTBI and HBV in patients prescribed biological therapy in a low-endemic area is 4.0% and 0.2%, respectively. Systematic screening by means of QFT and HBV serology seems more reliable than history taking and chest X-rays alone. Since implementation of systematic screening of IMID patients, no patients showed reactivation of LTBI or HBV during biological therapy.