In experimental investigations on Eimeria stiedai infected rabbits, serum enzymatic studies have been carried out in correlation with the examination of parasitological and pathological parameters. The rabbits were orally infected with a single dose of either 100,000 or 250,000 sporulated oocysts. Increase of the activity of the sorbit dehydrogenase (SDH), glutamate oxalate transaminase (GOT), glutamate pyruvate transaminase (GPT) and glutamate dehydrogenase (GlDH) could be found first between 3 and 10 days after infection indicating the beginning of the acute phase of liver coccidiosis. The increase of the conjugated bilirubin and of the gamma-glutamyl-transferase (gamma-GT) could be found not earlier than 10 days after infection and is to be explained as sign of disturbed efficiency of excretion. The various investigated parameters reached their peak of alteration about the end of the prepatent period and at the beginning of patency between 14 and 21 days after infection. The results emphasize the value and usefulness of serum enzymes, particularly the glutamate dehydrogenase (GlDH) and the gamma-glutamyl-transferase (gamma-GT) with about 30fold activity, as indicators in the course of Eimeria stiedai infection of rabbits. The enzymes returned to physiological values at the end of the experiment, 42 days after infection. Significant differences could not be detected within the infected groups. The activities of the alkaline phosphatase (AP), leucine aminopeptidase (LAP), choline esterase (ChE), lactate dehydrogenase (LDH) and isoenzym 1 (alpha-HBDH) showed only slight alterations and proved to be no significant parameters for the pathophysiological evaluation of the liver coccidiosis.