A case of bovine abortion was for the first time in Switzerland diagnosed by immunohistochemistry PCR (16S rRNA, ompA) and gene sequence analysis to be caused by Chlamydia psittaci. A possible occurence of further cases has to be investigated. Based on the existence of several methods with very different sensitivity and specificity to diagnose chlamydia it is suggested that at least two verified diagnostic tools should be used to diagnose an involvement of chlamydia in bovine abortion.