Fifteen cases of Q fever endocarditis that occurred in 1999-2000 in southern France are described and compared with 15 cases from the same area reported in 1987. Significant decreases were found in the prevalences of heart failure, hepatomegaly, inflammatory syndrome, anemia, leukopenia, and abnormal liver function test results in patients who had Q fever endocarditis after 1997. This was probably the result of a reduction in the delay before diagnosis of the disease and of the use of novel, effective antibiotic regimens.