Purpose: Lobular carcinoma in situ (LCIS) is a marker of increased risk of breast cancer. Current guidelines do not recommend mastectomy as a strategy for risk reduction for most patients with LCIS. We conducted a population-based study to evaluate national trends in incidence and management of LCIS. Methods: Using the Surveillance, Epidemiology, and End Results database, we conducted a retrospective cohort analysis of women diagnosed with microscopically confirmed LCIS from 2000 through 2009. We excluded patients with invasive breast cancer or ductal carcinoma in situ. We evaluated variation in treatment, including biopsy alone, excision, excision with radiation therapy, and mastectomy. We utilized logistic regression to identify time trends, demographics, and patient factors associated with mastectomy. Results: We identified 14,048 patients diagnosed with LCIS from 2000 to 2009. The rate of LCIS incidence increased from 2.0 per 100,000 in 2000 to 2.75 per 100,000 in 2009 (38 % increase). Of these patients, 10 % underwent biopsy only, 73 % underwent excision alone, 1 % underwent excision with radiation, and 16 % underwent mastectomy. Mastectomy rates were significantly higher among white and younger women. The proportion of women with LCIS to receive mastectomy increased by 50 % from 2000 to 2009 (p < 0.01). Mastectomy rates varied significantly based on geographic region ranging from 12 to 24 %. Conclusions: This is the first population-based analysis evaluating patterns and trends in surgical management of LCIS. Despite current recommendations, risk-reduction surgery is increasingly performed in the United States for women with LCIS.