Gastrointestinal stromal tumors (GIST) are tumors most frequently found in adults. They are often related to activating mutations in the CD-117 tyrosine kinase receptor, most commonly at exon 11. Gastrointestinal stromal tumors have been reported in children. However, until recently, there had not been reports of activating mutations in the CD-117 gene, and none have yet documented an exon 11 mutation. We report the case of a 17-year-old found to have an activating mutation in exon 11 of the CD-117 gene. This could play a role in treatment with the targeted therapeutic agent imatinib mesylate.