709 Background: A recent trial compared local radiation boost (RB) to no local boost (NB) following breast conservation therapy. Fewer local recurrences (LR) occurred in the RB group, most pronounced in patients ≤ 40 years old. The current study evaluates LR in young patients at an institution where RB is not routine. METHODS A retrospective review was performed on patients ≤ 40 years with primary breast cancer who underwent adjuvant breast radiation from 1980-1999. RB was added to patients at high risk for LR (close margins, multifocal tumors). RESULTS Seventy-five patients with a median age of 37 years (range 24-40) were followed for a median 7.6 years (range 0.5-17.7). Twenty-six patients received a RB while 49 patients were treated with uniform breast radiation only. Multifocal tumors, were more prevalent in the RB group (19% vs. 2%, p=0.03). LR occurred in 8 of 75 patients (11%). There was no difference in LR between NB group (3/49, 6.1%) and RB group (5/26, 19.2%)(p=0.18). LR in the same quadrant as the primary tumor was found in 2 patients in the NB group (4%) and 3 patients in the RB group (n=12%)(p=0.23). There were no significant differences in overall survival, disease-free survival, and same quadrant disease-free survival between the two groups. The addition of a radiation boost was not predictive of local recurrence by univariate and multivariate analyses. CONCLUSIONS Uniform breast irradiation resulted in low ipsilateral and same quadrant recurrence rates. Routine RB does not appear to be justified in young patients. No significant financial relationships to disclose.