Background <p>Colorectal cancer screening with fecal immunochemical testing (FIT) is a process that depends on diagnostic colonoscopy for those with a positive test and completion of colonoscopy after positive FIT is an essential element of program effectiveness.</p> Aims <p>We examined how the COVID-19 pandemic influenced completion of diagnostic colonoscopy after positive FIT in our integrated healthcare system.</p> Methods <p>This was a retrospective study of all positive FIT over a 5-year period. FITs were characterized as being done in pre-pandemic, early pandemic, or late pandemic time periods. The primary outcome was proportion of timely diagnostic colonoscopy completed within 6 months of positive FIT.</p> Results <p>Among 2157 patients with positive FIT, 50% received diagnostic colonoscopy within 6 months, 20% received colonoscopy after 6 months, and 30% received no colonoscopy. 56% of patients had timely colonoscopy during the pre-pandemic period as compared to 39% in the early pandemic and 49% in the late pandemic (<i>p</i> value &lt; 0.01 for all comparisons). Those who had their colonoscopy done via community care referral were less likely to do so within 6 months.</p> <p>Among patients with no colonoscopy, the most common reasons included patient declined (48%), clinicians deferred due to comorbid conditions (26%), or the patient died (21%).</p> Conclusions <p>Before and during the pandemic, we found low rates of completion of colonoscopy after a positive FIT, which highlights an important barrier to program effectiveness. Many FIT were inappropriate given the high proportion of patients who either died or were recommended not to complete a colonoscopy.</p>