A cross-sectional seroprevalence study using the complement fixation technique (CFT) was carried out among technical and support staff of the Department of Agriculture in Ireland (n=375). A result CFT of < 1:8 was accepted as normal, i.e., no evidence of exposure to Brucella abortus. Results were compared with available medical records to differentiate new from old or established cases. The participation rate was 75% (n= 281). Of the 281 participants, ten [3.6% (95% CI 1.7-6.5%)] tested positive (titers > or = 1:8). Veterinarians, laboratory staff, and workers based in meat plants were at increased risk of exposure. 106 previous results were available. Eight of those who tested positive had previously been tested, and of these, four (3.8%, 1-9.4%) had converted from negative to positive in the intervening five years, a conversion rate of 8 (CI 2-20) per 1,000 employees per annum. Thus, exposure to B. abortus remains common among at-risk occupational groups in Ireland.