The first trial in the developmental phase of the "Performance Evaluation Program" based on the new programs of the International Council for Laboratory Animal Science (ICLAS) was carried out. ICLAS supplied test samples to each diagnostic laboratory for self-assessment of microbiological monitoring methods. We found that 1 mouse serum sample was positive for mouse minute virus and another was positive for Mycoplasma pulmonis antibodies, and 1 rat serum sample was positive for Sendai virus antibody. Mouse parvovirus was detected from mouse spleen and mesenteric lymph node homogenate, and Helicobacter spp. were detected from mouse feces. Corynebacterium bovis was isolated from a mouse skin sample. These results were in agreement with those notified by the ICLAS after the trial. After this trial, the program will eventually be made available to all diagnostic laboratories willing to participate in it.