An environmental microbiological surveillance program was conducted throughout the dry milk industry in cooperation with the American Dairy Products Institute (ADPI). The purpose of the survey was to determine the frequency and location of certain pathogenic microorganisms in dry milk and whey processing plant environments. A total of 402 samples were collected from 18 plants by each respective plant's personnel. All plants participated on a voluntary basis in response to a request sent to all ADPI members. All 410 samples were tested for Listeria spp., 245 samples were tested for Salmonella , and 312 samples were tested for Yersinia . Of the total, five samples collected from five separate plants were positive for either Salmonella or Listeria . Two samples were positive for Listeria (one for L. monocytogenes ), and three samples were positive for Salmonella . None was positive for Yersinia . Four out of the five positive samples were taken from drains in receiving, dryer, and butter production areas of the plants. The fifth positive sample was collected from a prefilter to a dryer.