A provisional diagnosis of babesiosis was made in a reindeer herd in Scotland when seven animals died during 1997 and 1998. Additional clinical cases occurred, but the animals recovered after treatment. Thirty-one reindeer from the herd were tested for the prevalence of exposure to Babesia by the indirect fluorescent antibody test using a bovine isolate of Babesia divergens that had been passaged through gerbils. Infection rates were determined by Giemsa-stained blood smears. In addition, molecular identification of the infecting Babesia sp. was undertaken using SSU rRNA gene sequence analysis. It is likely that the organism causing babesiosis in this reindeer herd is B. divergens. Reindeer and blood samplesThirty-one reindeer of known age and sex, owned by the Cairngorm Reindeer Centre, were used in this study (Tables 1, 2). All animals were from a group of 70 housed off public display at the