Discrimination by automatic ribotyping and random amplified polymorphic DNA PCR, RAPD, was compared for 40 different B. cereus dairy isolates, 4 different B. mycoides isolates and 6 culture collection strains. RAPD-PCR has previously shown to be useful for tracing contamination routes of B. cereus to milk. Automatic ribotyping using EcoRI and PvuII separated the B. cereus and B. mycoides isolates/strains into 36 different ribotypes. RAPD-typing with primer 1 (5?-CCGAGTCCA-3?) and primer 2 (5?-CCGGCGGCG-3?) generated 40 different RAPD-profiles. However, 17 isolates clustered into 8 groups, irrespective of the primer and restriction enzyme used and in all but one case, the isolates with the same pattern were isolated from the same dairy. To conclude RAPD-typing was only slightly more discriminatory than automatic ribotyping and therefore automatic ribotyping proved to be a useful, standardized and quick method to discriminate between B. cereus strains. As the two methods are based on completely different genetic properties, one of the methods can be used to confirm the results from the other method, when identity among isolates needs to be verified.