Sarcomas are rare neoplasms, accounting for a 1.7% incidence among all transplanted patients presenting with de novo malignancies. Our present report focused on a 46-year-old woman who received immunosuppressive therapy based on cyclosporine and steroids for renal transplantation. Eight years after transplantations, she suffered lower abdominal pain and a mass involving peritoneal soft tissues was located near the right iliac vessels. Upon radical tumor excision, the histological examination revealed a high-grade leiomyosarcoma. Immunosuppression was reduced and cyclosporine switched to rapamycin. After 30 days, a computed tomography scan revealed two small pulmonary metastases, so the patient received adriamycin. Six months after the diagnosis, there was no intra-abdominal relapse and the pulmonary metastasis remain stable. The function of the transplanted kidney was normal and the patient was listed for laparoscopic pulmonary resection. Sarcomas in solid organ transplant patients appear to have aggressive features with 62% being high grade and 40% metastatic at the time of primary diagnosis with a recurrence rate of 30% and a 5-year survival rate of 25%. Patients diagnosed with sarcoma should be treated with multimodality therapy. After aggressive surgery whenever possible, a combination of a traditional cytotoxic drug and a "signal" blocking agent like rapamycin may increase selectivity toward tumor cells.