BACKGROUND There are radiobiologic and technical advantages to the use of interstitial brachytherapy alone or as an adjunct to external beam radiotherapy in the postoperative treatment of soft tissue sarcomas. OBJECTIVE To review the experience of the Rambam Medical Center in implementing interstitial brachytherapy in the treatment of 32 patients with soft tissue sarcomas. METHODS Thirty-two patients with variously located soft tissue sarcomas were managed with a combination of surgery and brachytherapy of the tumor bed, with or without EBRT. In 27 of 32 patients, brachytherapy catheters were placed intraoperatively, while in 5 patients the implant was performed as a separate postoperative procedure. Twenty-seven patients received low dose-rate brachytherapy with Iridium-192 seeds. Five patients received fractionated high dose-rate brachytherapy using the microSelectron machine. RESULTS With a median follow-up of 36 months, the overall local control rate was 87.5%. Four of 32 patients (13%) failed locally at the implant site, and 6 (19%) developed lung metastasis. Two of the five patients with lung metastasis had a local recurrence as well. At the time of analysis, eight patients had died of sarcoma (disease-specific mortality rate was 25%), while three had died of intercurrent causes. The 5 year actuarial disease-free survival rate was 56%, and the 5 year actuarial overall survival 70%. Five patients (16%) developed severe wound complications following surgery/brachytherapy, and six patients (19%) developed late local toxicity (fibrosis and telangiectasia). CONCLUSIONS Wide local excision followed by interstitial brachytherapy has resulted in an 87.5% local control rate with a 16% local complication rate.