BACKGROUND AND STUDY AIMS: The Paris classification characterizes the morphology of superficial gastrointestinal tract neoplasms. This system has been shown to predict the risk of submucosal invasion in certain subtypes of lesions. There is limited data that assesses its agreement amongst endoscopists. We performed a systematic review to summarize the available literature on the interobserver reliability (IOR) of the Paris classification. METHODS: We conducted a search through December 2020 for studies reporting IOR of the Paris classification. Studies were included if they quantitatively evaluated the IOR of the Paris classification with at least five participating endoscopists. Two authors independently screened studies and abstracted data using an a priori-designed data collection form. Evaluation of study quality and risk of bias was performed using an adapted version of the Guidelines for Reporting Reliability and Agreement Studies. RESULTS: Of the 1,541 studies retrieved, 5 were included in the review. All studies were observational cohort studies published between 2014 and 2020. The IOR of the Paris classification was moderate amongst all four studies evaluating colorectal neoplasms (range, κ = 0.42 to κ = 0.54) and substantial in one study that evaluated gastric neoplasms (κw = 0.65). An educational intervention was conducted by three studies with variable methodology and no significant change in IOR. CONCLUSIONS: IOR of the Paris classification is moderate for superficial colonic neoplasms. Further study is needed to determine the reliability of this system for superficial gastric lesions. Standardized training programs are required to investigate the impact of educational intervention on the Paris classification amongst endoscopists.