Reconstruction rates after mastectomy have been reported to range from 25-40%; however, most studies have focused on patients treated in an inpatient setting. We sought to determine the utilization of outpatient mastectomy and use of breast reconstruction in Southern California. Postmastectomy reconstruction rates were determined from the California Office of Statewide Health Planning and Development database from 2006-2009 using CPT codes and similarly from an inpatient database using ICD-9 codes. Reconstruction rates were compared between the inpatient and outpatient setting. For the outpatient setting, univariate and multivariate odds ratios with 95% confidence intervals were estimated for relative odds of immediate reconstruction versus mastectomy alone. The percentage of patients undergoing outpatient mastectomy ranged from 20.4 to 23.9% of the total number of all patients undergoing mastectomy. Whereas immediate inpatient reconstruction increased from 29.2 to 41.6% (overall rate 35.5%), the proportion of outpatients undergoing reconstruction only increased from 7.7 to 10.3% (overall rate 9.1%). Similar to the inpatient setting, in multivariate analysis, age, insurance status, race/ethnicity, and type of hospital were significantly associated with the use of reconstruction in the outpatient setting. A substantial number of patients undergo outpatient mastectomy with low rates of reconstruction. Although the choice of an outpatient mastectomy may certainly represent a selection bias for those not choosing reconstruction, an increase in the use of outpatient mastectomy may result in decreases in the use of postmastectomy reconstruction.