To compare completion rates of colorectal cancer screening tests within a health maintenance organization before and after widespread adoption of the fecal immunochemical test (FIT). Retrospective cohort study. Using electronic medical records of 113,901 patients eligible for colorectal cancer screening, we examined test completion during 2 successive time periods among those who received an automated screening outreach call. The time periods were: 1) the "guaiac fecal occult blood test (gFOBT) era," a 15-month period during which only gFOBT was routinely offered, and 2) a 9-month "FIT era," when only a new FIT was routinely offered. In addition to analyzing completion rates, we analyzed the impact of practice-level variables and patient-level variables on overall screening completion during the 2 different observation periods. The change from gFOBT to FIT in an integrated care delivery system increased the likelihood of screening completion by 7.7% overall, and the likelihood of screening with a fecal test by 8.9%. The greatest gains in screening completion using FIT were among women and elderly patients. Completion of FIT was not as strongly associated with medical office visits or with having a primary care provider as was screening with gFOBT. Adoption of FIT within an integrated care system increased completion of colon cancer screening tests within a 9-month assessment period, compared with a previous 15-month gFOBT era. Higher completion rates of the FIT may allow for more effective dissemination of programs to increase colorectal cancer screening through centralized outreach programs.