OBJECTIVES:  Overall survival (OS) has significantly improved over the last decade for patients with metastatic colorectal cancer (mCRC) due to advances in systemic chemotherapy, targeted agents, and supportive care. Duration and sequencing of therapies have correlated with OS. We aimed to describe duration of first line (1L) treatment among patients with mCRC in the community setting. METHODS:  Patients with mCRC diagnosed from 2012–2014 (ICD-9 codes 153.x, 154.0x, or 154.1x and 197.x–198.x) were identified from a US healthcare claims database consisting of 129 million unique covered patient lives. Patients were classified into treatment groups based on 1L treatment received. Treatment duration (TD) was defined as time from initiation to 30 days prior to initiation of 2L or end of follow-up and calculated by Kaplan-Meier estimator (median and 95% CI). Log-rank test assessed equality of survivor functions (i.e., time to 1L discontinuation). RESULTS:  There were 4,527 mCRC patients identified (mean age at diagnosis, 61.2 years; 54% male) who initiated 1L therapy. On average (mean, SD), patients were followed for 12.8 months (8.47 months) after diagnosis. Median 1L TD was 211 days (95% CI: 204 days, 221 days) across all treatments. The longest 1L median TD was 250 days (95% CI: 239 days, 262 days) among those treated with a biologic + fluoropyrimidine (FP) + chemotherapy, followed by 217 days (95% CI: 202 days, 237 days) among those treated with FP + chemotherapy, followed by 178 days (95% CI: 148 days, 280 days) among those treated with biologic + FP, and 141 days (95% CI: 133 days, 151 days) among those treated with FP monotherapy (p<0.0001). CONCLUSIONS:  These real world data show significant variability in the duration of 1L treatments among patients with mCRC. The choice of 1L therapy may have an impact on the time to treatment discontinuation.