[Show abstract][Hide abstract] ABSTRACT: Post-partum metritis cases in a dairy herd milking 400 cows were investigated by means of a within-herd case control study. Fifteen affected (case) and fifteen unaffected (control) cows were sampled in the post-partum period for bacteriology and virology. Arcanobacterium pyogenes were isolated from vaginal swabs from ten cases but no controls. Bovine lymphocytic herpesvirus and Bovine herpesvirus-4 were detected by PCR testing in similar numbers of cases and controls although BoHV-4 was not detected in vaginal swabs in control animals. Non-infectious factors also played a part in the metritis problem.