The incidence of basal cell carcinomas (BCCs) is increasing globally, but incidence rates in the United States are difficult to quantify because BCCs are not reportable tumors. To estimate annual BCC incidence rates by age, sex, and race/ethnicity to identify demographically distinct high-risk subgroups and to assess changes in rates over time. In this retrospective cohort study (January 1, 1998, through December 31, 2012), we studied 147?093 patients with BCC from Kaiser Permanente Northern California, a large, integrated health care provision system, identified using a previously validated BCC registry. We estimated annual BCC incidence rates by age, sex, and race/ethnicity and assessed changes in rates over time. The BCC incidence rates were standardized to the age, sex, and race/ethnicity distribution of the 2010 US Census population. In models adjusting for age, sex, and race, male patients had higher rates than female patients (incidence rate ratio [IRR], 1.65; 95% CI, 1.60-1.70). Persons 65 through 79 years of age and those 80 years and older had higher rates than persons 40 through 64 years of age (IRR, 2.96; 95% CI, 2.86-3.06; and IRR, 5.14; 95% CI, 4.94-5.35, respectively). Whites had higher rates than multiracial persons (IRR, 1.96; 95% CI, 1.80-2.13), Hispanics (IRR, 8.56; 95% CI, 7.79-9.41), Asians (IRR, 33.13; 95% CI, 27.84-39.42), and blacks (IRR, 72.98; 95% CI, 49.21-108.22). We estimate that BCCs occur in?approximately 2 million Americans annually. Our findings provide an updated estimate of the incidence of BCCs, highlight the changing epidemiologic findings, and better identify demographically distinct high-risk subgroups.