To report the 5-year minimum follow-up in low-risk breast cancer patients treated with a double-lumen balloon-brachytherapy device in one mono-institutional Italian experience. Local control data and cosmetic outcomes were collected and analyzed. Between October 2004 and December 2007, we treated 30 early stage breast cancer patients who underwent conservative surgery followed by adjuvant accelerated partial breast irradiation with a double-lumen balloon-brachytherapy system. Eligibility criteria for the protocol were based on the indications of the American Brachytherapy Society and the American Society of Breast Surgeons. The device was placed inside the lumpectomy cavity during surgery by open technique in all the patients. Computed tomography images and standard X-ray were used for treatment planning. The total irradiation dose was 34 Gy in 10 fractions of 3.4 Gy (twice daily) over 5 days to the lumpectomy cavity. Median follow-up was 80.5 months (range, 60-98). No patient developed local recurrence or distant metastasis. At the end of treatment, there was evidence of a symptomatic seroma in 83% of the total patients, with a yearly decreasing trend. However, the incidence of mild and moderate fibrosis progressively increased. Seventy-seven percent of the patients were satisfied with their cosmetic results. Our findings reinforce the hypothesis that an accelerated double-lumen balloon-breast brachytherapy catheter in selected low-risk patients is safe, and a favorable cosmetic outcome can be achieved.