Introduction: Colorectal cancer (CRC) is one of most common cancer worldwide. Colonoscopy plays a critical role in colorectal cancer screening decreasing the incidence of CRC by allowing early detection and removal of precancerous lesions. Adenoma detection rate (ADR) and cecal intubation rate (CIR) are key quality indicators in endoscopy. Aims: To evaluate the quality of colonoscopy in different eras of endoscopy. To assess the impact of technological advancement. To evaluate the effectiveness of colonoscopy performed by general surgery residents. Materials and methods: The study enrolled colonoscopy as a part of a national CRC screening program between 2000 and 2018. Quality indicators, patient- related factors, impact of technology, physician abilities were analyzed. Results: The ADR, CIR patient tolerance were significantly higher inexaminations performed with technologically advanced endoscopes. Mean cecal intubation time was shorter increased loop formation was observed in modern endoscopes group. They caused less discomfort and pain (VAS: 2.3 vs. 2.6). CIR was 95.99%, equal for residents and consultants (p=0.994). There was no statistically significant difference ADR 29.30% residents vs 27.66% consultants (p=0.203). Patient tolerance for exam was very good (4-point scale) - 78.98% consultants vs 75.18% residents (p<0.001). Conclusions: Patient-related factors a great influence on the effectiveness of the CRC screening program. Technological innovations significantly improve the quality of CRC screening. Residents are able to perform high quality screening colonoscopy.