Background: Standardized synoptic reporting has become widely adopted for cancer pathology reporting to ensure inclusion of all important pathologic data, which in turn helps guide treatment decisions and inform prognosis. In 2015, mandatory synoptic reporting for colorectal (CRC) resections was implemented in Nova Scotia’s largest pathology laboratory. This study evaluated the impact of that implementation on report completeness, adherence to individual reporting elements, adequacy of lymph node staging, and differences between subspecialist gastrointestinal (GI) and non-subspecialist pathologists. Methods: CRC pathology reports from the Nova Scotia Health Central Zone were reviewed for three time periods in relation to synoptic reporting implementation: before (2013 - 2015), a transition period (2015 - 2017), and after (2018 - 2020). We extracted basic demographic information, adherence to each element of the synoptic template, information about lymph node assessment, and whether the report was completed by a subspecialist GI or non-subspecialist pathologist. Results: 1568 CRC resection reports were analyzed. Overall completeness improved from 79.2% before mandatory synoptic reporting to >86% after implementation. Several previously underreported mandatory elements, including macroscopic tumour perforation, perineural invasion, and overall margin status, showed improvement, as did two mandatory elements for rectal cancers (tumour location relative to peritoneal reflection and macroscopic mesorectal intactness). The proportion of cases with inadequate lymph node examination (Conclusions: Mandatory synoptic reporting has significantly enhanced the quality and completeness of CRC pathology reports in our centre, as well as adherence to key quality indicators like adequate lymph node sampling. Synoptic reporting represents an effective and durable quality improvement intervention in surgical pathology practice.