Group B streptococci commonly colonize parturient women, yet pregnancy-associated endocarditis due to this organism is rare. Most reports of group B streptococcal endocarditis are from the preantibiotic era and occurred in women with rheumatic mitral valve disease. Reported herein are two cases of fatal group B streptococcal endocarditis involving the aortic valve of women with no preexisting heart disease. One had undergone a second-trimester abortion and the other had a normal pregnancy and uncomplicated vaginal delivery.