A 17-year-old female patient with a history of surgery for primary femoral and metastatic lung osteosarcoma was admitted to our clinic with palpitations. Upon evaluation, a metastatic osteosarcoma in the left ventricle was diagnosed. Based on the collaborative decision of the oncology and cardiovascular surgery clinics, surgery was performed and the patient was discharged without any problems. According to the recommendation of the oncology clinic, chemotherapy was postponed for 6 months after surgery. Five months post-operatively, however, she had a recurrence with 2 tumors. Based on the collaborative decision, chemotherapy was initiated and in 2 months the size of the recurrent tumors had diminished. The patient is still under the care of the oncology and cardiovascular surgery clinics and continuing her chemotherapy regimen.