This study was designed to evaluate the performance of culture methods and media types used for the isolation of Mycobacterium avium sp. paratuberculosis (MAP) in laboratories around the world. Recently, there have been advances for the detection of MAP including PCR, as well as enhancement of the standard culture method, liquid culture and the use of various types of solid media. This study compares the performance of these techniques in an effort to determine the most sensitive culture method and media currently available. Each participant received 30 coded fecal samples and 60 tubes of Becton Dickinson Herrold's Egg Yolk Media (HEYM). The fecal set consisted of 4 negative and 26 culture positive animals: 7 high, 8 moderate, 5 low and 6 intermittent shedders. Each laboratory was instructed to culture these samples according to their current protocol and inoculate two tubes of the BD HEYM and two tubes of their standard media. Each lab was required to submit 25 tubes of their media for a comparison using the standard three-day culture technique. Of the 30 laboratories results have been received from 16. In 60% of the samples the in-house media detected more positives. In 10% the BD HEYM detected more positives. In 30% the two medias were equal. The highest number of positives detected via standard fecal culture was 23/30 with an average of 16. Of the 16 labs from which results have been received five labs performed the liquid culture. The highest number of positives detected via liquid culture was 19/30 samples with an average of 13. Two labs performed diagnostic PCR on the fecal sample directly. One lab detected 53% and the other detected 43%. The results from the second part of this study to evaluate the media from each lab will not be available until May 2002.