We present a case of subacute bacterial endocarditis in a 10-year-old girl with Di-George syndrome, congenital heart disease, and mild immunodeficiency. She was afebrile at initial presentation but was found to have massive splenomegaly, and signs of congestive heart failure. No causative organism could be identified on routine blood and tissue cultures. A detailed clinical history revealed a history that she had been scratched by a cat and developed intermittant fevers over 3 months. Bartonella henselae was identified by broad-range 16S r-DNA polymerase chain reaction on valvular tissue specimens.