Myxomas are low-prevalence heart tumors in the pediatric population. They are located in the left atrium in 75-86% of cases, and 30-50% are accompanied by general symptoms such as fever, weight loss, myalgias, arthralgias and elevated inflammatory markers caused by IL-6 release. They are rapidly growing heart tumors, and their most important complications are valvular and ventricular inflow tract obstruction, which may cause sudden death. Three to ten percent of cases are associated with Carney complex (CNC), type 1, caused by a mutation of the PRKAR1A gene on chromosome 17. We present the case of a 10-year-old girl with general symptoms, a murmur, syncope, hemolytic anemia and multiple nevi, in whom a giant obstructive myxoma was found in the left atrium. Carney complex, type 1, was confirmed. She underwent successful surgical resection with no complications.