The European Union Reference Laboratory for Feed additives (control) (EURL-FA (control)) has been mandated by the Directorate General for Health and Consumers (DG SANCO) to organise an interlaboratory comparison (ILC) among appointed National Reference Laboratories (NRLs) in order to assess their capacity to correctly determine the 11 authorised coccidiostats at cross-contamination levels in feed matrices. Other EU control laboratories and one laboratory from Switzerland also joined the exercise. This report presents the results of the proficiency test (PT). Thirty-two laboratories from 22 countries registered to the exercise. Three test items were produced, homogenised and distributed by the EURL-FA Control. Two contained 4 and 3 selected coccidiostats respectively and the third one was a blank. Laboratory results were rated using z- and ?-scores (zeta-scores). Between 64% and 80 % of the laboratories reported satisfactory results for monensin, narasin, nicarbazin and maduramicin. For lasalocid, only 59 % of the laboratories submitted satisfactory results, 58% for diclazuril and 53% for halofuginone. The results are summarised in the following Table 1. The laboratories also reported qualitative results as regards the presence of one or more of the other authorised coccidiostats. On the whole, the rate of false positive results was 3% for lasalocid, 4% for maduramicin, 5% for halofuginone and 0% for all the others.