Two non-splenectomized reindeer developed fever, icterus and haemoglobinuria after inoculation intravenously with cattle blood containing Babesia divergens. 14 and 15 days after inoculation agglutination of Babesia-containing erythrocytes from the two reindeer was observed in blood films. In one reindeer there was also microscopical evidence of intravascular agglutination in the sinusoids of the spleen. As a control, a non-splenectomized reindeer calf was inoculated with normal cattle blood; there were no signs of agglutination.