Objectives This study sought to evaluate the outcome of maternal autoantibody-mediated fetal cardiomyopathy/endocardial fibroelastosis following intravenous gamma globulin (IVIG) and corticosteroid therapy. Background We have previously shown that 85% of fetuses and infants with maternal autoantibody-mediated fetal cardiomyopathy/endocardial fibroelastosis suffer demise or need for transplant. In an attempt to improve this outcome, in 1998, we began to empirically treat affected patients with IVIG and corticosteroids. Methods We reviewed the clinical records and echocardiograms of 20 affected patients encountered in our institutions and treated with IVIG and corticosteroids from 1998 to 2009. Results All 20 were initially referred at a median gestational age of 23 weeks (range 18 to 38 weeks). Nineteen mothers were anti-Ro antibody positive, 8 anti-La antibody positive, and 7 had clinical autoimmune disease. Endocardial fibroelastosis was seen in 16 and was not obvious in 4 others with reduced ventricular function, and 16 (80%) had reduced or borderline ventricular shortening fraction (≤30%) before or after birth. Eighteen had atrioventricular block at referral (16 in 3°). During pregnancy, maternal IVIG was given in 9 and dexamethasone in 17. After birth, 17 infants received IVIG (n = 14) and/or corticosteroids (n = 15). Twelve underwent pacemaker implantation. Four with hydrops at presentation died perinatally, despite initial improvement in function in 3. At a median follow-up of 2.9 years (1.1 to 9.8 years), 16 (80%) patients are currently alive with normal systolic ventricular function and 6 are not paced. Conclusions Treatment of maternal autoantibody-mediated fetal cardiomyopathy/endocardial fibroelastosis with IVIG and corticosteroids potentially improves the outcome of affected fetuses. Further studies are needed to determine the optimal dose and timing of IVIG administration.