Chlamydial infections have been reported to be linked to a broad range of conditions in cattle, including respiratory, enteric and reproductive infections. However, relatively few studies have investigated the prevalence of chlamydial infections in cattle, and reports vary hugely in terms of prevalence rates. In order to assess the prevalence in the Republic of Ireland, advantage was taken of bovine serum samples that had previously been collected for Brucella screening. Two thousand cows from 100 herds (20 per herd) were screened by SolPr indirect ELISA, which detects the two most common Chlamydiaceae spp. affecting cattle, namely Chlamydophila abortus and Chlamydophila pecorum. A total of 95 samples from 57 herds were deemed positive representing a prevalence rate of 4.75%, while 19, 4, 1 and 2 herds recorded 2,3,4 and 5 positive samples, respectively. The parametric bootstrap estimate of the mean disease prevalence (%) in the population was 6.04 (95% confidence interval 4.70 to 7.50). There was no association between higher prevalence rates and any known reproductive issues in specific herds . A further 36 samples obtained from cases of undiagnosed abortion were found to be negative for chlamydial antibodies by both SolPr ELISA and immunoblot analysis. The results suggest that chlamydial infection is very low in Irish cattle.