A ring test was organized for the detection of animal proteins in animal feed by microscopy in the framework of the annual ring tests of the IAG - International Association for Feeding stuff Analysis, Section Feeding stuff Microscopy. The aim of the ring study was to provide the participants information on the local implementation of the detection method for their individual quality systems. A further aim was to gather information about the application of the microscopic method. Of the four samples prepared three were based on a ruminant feed as matrix: one containing no animal proteins (blank), one with 0.1% of land animal material, and one with 0.02% of land animal material. The fourth sample consisted of a fish meal fortified with 10% of salmon material. All participants were requested to determine the presence or absence of land animal and/or fish protein material and to indicate the type of material found. Specificity scores for the feed samples were all slightly below 0.95. The detection of the materials of land animals was good in all cases. The presence of material of land animals in the fortified fish meal was indicated in a series of occasions (16 false positives out of 53 observations). Although it can not be ruled out that an occasional trace of avian material is present in a fish meal, this specificity score of 0.70 can be considered to be mainly the effect of the difficult discrimination between salmon bone fragments and land animal material. The staining of the sediment with Alizarin and the use of a binocular appear to influence notable or even considerable the results in terms of specificity and sensitivity. A further harmonization is still possible.