The aim of this study was to investigate the seroprevalence of ovine chlamydiosis caused by Chlamydia abortus in sheep and goats in Western Turkey. Chlamydial abortion causes late term abortions with a worldwide occurence particularly in sheep and goats; it also leads to significant financial losses. Seroepidemiological studies provide useful data regarding the prevalence of the disease. Isolation of Chlamydia abortus as the causative agent of the disease is a time consuming and laborious procedure requiring appropriate biosafety measures. Serological methods are commonly used for routine diagnosis and enzyme-linked immunosorbent assay is generally recommended for surveillance studies. In this study, a total of 833 blood samples obtained from 126 herds of sheep and goats located in all provinces of the Marmara region, Western Turkey, were analyzed. Total seroprevalence was found to be 25.81% through enzyme-linked immunosorbent assay. However, the proportion of seropositive herds was observed at 62.70%, which is higher than the total seroprevalence. This study confirms the presence of Chlamydia abortus exposure in sheep and goat herds in the Marmara region and provides original seroprevalence data in the provinces, which have not been reported so far. The data gathered are useful for the evaluation and elaboration on the seroprevalence of chlamydiosis in small ruminants in the Marmara region, Turkey.