Li-Fraumeni syndrome and the LF-like syndrome, rare heritable conditions that predispose to the development of malignancy, are associated with germline mutations of the tumor suppressor gene p53. The authors describe a 14-month-old boy who presented with synchronous rhabdomyosarcoma and adrenal cortical carcinoma and a novel mutation of the p53 gene. Analysis of exons 2 through 11 of the p53 gene using the polymerase chain reaction and DNA sequencing revealed a mutation of codon 273. Although codon 273 is a known hotspot region for p53 mutation, the patient's mutation, R273H, has not been associated with development of adrenal cortical carcinoma.