Aims: Clinical laboratories play a vital role in healthcare, yet their operations contribute to resource consumption, waste generation, and greenhouse gas emissions. The need for sustainable practices in laboratories has led to guidelines for reducing their carbon footprint. This study aims to assess the impact of sample rejection rates (SRRs) on laboratory sustainability by calculating the carbon footprint and medical waste generated due to rejected samples.Methods: This retrospective, single-center study obtained data from the Hospital Information Management System for two years (2021 and 2022). SRRs were calculated for different sample tube types. The carbon footprint caused by rejected samples was calculated using CO2 emission (CO2e) conversion factors. The weight of medical waste generated due to rejected samples was evaluated. Statistical analysis was performed using appropriate tests.Results: In 2021 and 2022, SRRs for different sample tubes were calculated, with statistically significant differences observed. The total CO2e value resulting from rejected samples over two years was 12.3 tons, and the medical waste generated was 3.7 tons. The highest SRR was observed in Blue top tubes, while yellow top tubes showed a significant reduction in SRR in 2022.Conclusion: This study highlights the impact of SRRs on laboratory sustainability. The calculated CO2e and medical waste values underscore the need to minimize sample rejections. While these values seem minor compared to global emissions, they reflect only a portion of the potential environmental impact. Reducing sample rejections not only improves patient safety and laboratory efficiency but also aligns with the larger goal of creating environmentally conscious and sustainable healthcare practices.