A 52-year-old woman with fever and low grade hepatitis had Q fever, a diagnosis made by the characteristic granulomas, containing fibrin and vacuoles, on liver biopsy and confirmed by serology. Fibrin was demonstrated in the granulomas but Coxiella burnetii antigens were not. The literature on the histopathology of the liver in both acute Q fever and Q fever endocarditis shows that none of the 220 cases of Q fever endocarditis, with one possible exception, had the characteristic granulomas of acute Q fever. Rather they displayed a range from normality through nonspecific reactive hepatitis to occasional nonspecific granulomas. Thus, the characteristic granulomas of acute Q fever appear to be transient even if active infection persists. The definition of chronic Q fever should have a temporal characteristic rather than a serologic one.