A study of the possible difference in outcome for positive margins for invasive carcinoma (IC) versus ductal carcinoma in situ (DCIS), and with regard to different age categories in a large prospective cohort of patients with invasive breast cancer. A total of 2 291 BCT were analyzed. Margins were positive for IC in 8.7% and for DCIS in 4.6%. The median follow-up was 83 months. The 10-year local recurrence-free survival for negative margins vs. positive margins for IC vs. positive for DCIS for women ≤40 years were 84.4% vs. 34.6% (HR 4.5) vs. 67.5%, and for women >40 years 94.7% vs. 92.6% vs. 82.6% (HR4.2). The 10-year distant disease-free survival for negative margins vs. positive margins for IC vs. positive for DCIS women ≤40 years were 72.0% vs. 39.7% (HR 3.4) vs. 77.8%. The disease-specific survival showed a significant relation to positive margins for IC in young women. The effect of positive margin for IC seems to be limited to young women only, and is not only restricted to local control, but also to distant metastasis and survival. On the other hand a positive margin for DCIS is a risk factor for local control in women >40 years.