OBJECTIVES: Evidences-based literature has confirmed the effectiveness of radiation therapy (RT) following breast conserving surgery (BCS); thus several practice guidelines recommend RT after BCS. This study explored factors associated guideline compliance among young women with insurance because compliance in this population is not well-understood. METHODS: Using the 2004-2009 MarketScan®Research Database, we identified our study cohort as women who had a BCS between July 1, 2004 and December 31, 2008, and had continuous enrollment from 6 months before to 12 months after the date of BCS. We excluded patients who had mastectomy within 3 months of BCS. We used Pearson Chi-Squared test and multivariate logistic regression to ascertain factors associated the receipt of RT within one year of BCS. We performed Hosmer-Lemeshow goodness-of-fit and other model diagnostic tests to determine the final model specification and conducted all analyses using SAS® 9.2 and Stata® 11.0 software. RESULTS: A total of 20,756 of the 24,011 (86.44%) BCS patients received RT within a year of their surgery. Results from the logistic regression showed that the odds of RT increased with age, compared with patients under 40, the odds ratio was 1.63 (95% confidence interval: 1.40-1.90), 1.86 (1.61-2.16), and 2.04 (1.73-2.39) for those in 40-49, 50-59, and ≥ 60 age group, respectively. Patients who did not enroll in HMOs (1.27; 1.17-1.37) and was primary insurance policy holder (1.31; 1.21-1.41) were significantly more likely to receive RT. Compare with patients resided in the Northeast region, those in the West were less likely to receive RT (0.71; 0.62-0.82). Positive association with hospital density was also observed (1.17; 1.04-1.31).  CONCLUSIONS: Although the compliance rate among young women with employment-based insurance was higher than that reported among the elderly (74.21%), significant variations across age groups, regions, and insurance types observed in this well-insured group call for future research to better understand reasons behind these variations.