Dermatofibrosarcoma protuberans is a soft-tissue tumor that may recur locally and rarely causes metastases to vital organs. Dermatofibrosarcoma protuberans has specific chromosomal abnormalities involving the platelet-derived growth factor β-chain locus that may render these tumors responsive to targeted therapy with the tyrosine kinase inhibitor imatinib mesylate. A patient with locally recurrent and metastatic dermatofibrosarcoma protuberans who had already undergone surgery 22 times was initially treated with imatinib mesylate 400 mg/day. The treatment dose was increased after 7 days to 400 mg twice daily. The patient was followed up for response and toxicity by physical examination and imaging studies, comprising computed tomography and fluorodeoxyglucose positron emission tomography. Clinical response could be demonstrated after the first month of treatment, and subsequent computed tomography and positron emission tomography documented a response to imatinib mesylate therapy. Our patient is now in sustained remission with minimal toxicity. We conclude that antitumor activity of metastatic dermatofibrosarcoma protuberans can be obtained with imatinib mesylate treatment with minimal side-effects.