BackgroundThe COVID-19 pandemic has affected all aspects of the healthcare system, including prevention, treatment, rehabilitation of diseases and health education; access to essential therapies; allocation of finance & facilities to health issues, and governance of diseases, including COVID-19 and other diseases. Consequently, the burden of COVID-19 was not only attributable to the multiorgan involvement and detailed presentation of the disease but also to the inadequate management of other diseases resulting from the exclusive allocation of resources and medical personnel to the pandemic crisis. Over the mentioned period, one observed deficiency was the lack of public and official favor for conventional screening protocols. To this end, this study aims to evaluate the impact of the COVID-19 pandemic on colorectal cancer (CRC) screening protocols at Shahid Beheshti University of Medical Sciences in Tehran, Iran, in an effort to identify individuals at risk for CRC and provide them with intensive screening and therapy.MethodsThis is an observational study comparing the number of candidates for CRC screening referred to primary, secondary, and tertiary health-care centers under supervision of Shahid Beheshti University of Medical Sciences (SBMU), Tehran, Iran in a 2-year interval before and after COVID-19 pandemics. Patients with intermediate- and high-risk criteria for colorectal cancer were included in the study and were screened by fecal immunochemical test. Patients with positive or indeterminate fecal test results were further evaluated with colonoscopy in research institute for gastroenterology and liver diseases where is a tertiary referral center for CRC screening. Finally, the decrease percentage of screening tests and endoscopic findings during the pandemic period compared to pre-pandemic period was calculated and interpreted.ResultsA significant decrease in the number of performed fecal immunochemical tests (FITs), referred positive FITs, and referred patients with positive alarm signs to the Research Institute of Gastroenterology and Liver Diseases (RIGLD) center inevitably led to a considerable decrease in the number of endoscopic findings, including high-risk adenomas, sessile serrated polyps, and even early-stage colorectal cancers (CRCs).ConclusionThe disruption of screening protocols caused by the COVID-19 pandemic appears to increase the number of patients with high-grade and end-stage CRCs referred in the near future.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12885-023-11111-x.