There is a fundamental lack of knowledge regarding optimal dosing of anti-cancer agents for young children with cancer, with resultant increased risk of morbidity, mortality and inferior outcome. Of the anti-cancer agents used frequently in infants and young children, the drug with the least amount of knowledge is actinomycin-D. Actinomycin-D, has been used for the treatment of several childhood cancers since the 1960s. Despite its longstanding and widespread use in pediatric oncology, there is virtually no pharmacokinetic information from which safe and appropriate age-based pediatric dosing can be derived. Actinomycin-D is an integral component of rhabdomyosarcoma and Wilms tumor therapy, and pediatric oncologists will continue to administer the durg despite the gap in knowledge.