Patient knowledge about lower endoscopy might have beneficial effects on satisfaction outcomes, pre-procedure anxiety, and adherence, although this is poorly understood. Methods Searching the national and international literature, we reviewed 20 years of observational studies and randomized trials that examine possible relationships between educating patients about lower endoscopy and clinical outcomes. Twenty-three publications were included but their heterogeneity precluded meta-analyses. Standard and modified informed consent procedures and enhanced educational interventions were associated most often with levels of patient knowledge, satisfaction, anxiety, and adherence. Regardless of the approach, a large proportion of patients have poor comprehension of lower endoscopy’s risks, benefits, and alternatives; patient satisfaction with information and procedures manifests ceiling effects; only a subset of patients have clinically significant pre-procedure anxiety; and providing written information and reminders may improve procedure adherence. Future work should focus on strategies for improving patient knowledge in the setting of initial screening colonoscopy within open access systems. Patient knowledge of lower endoscopy is often inadequate even though greater knowledge might be associated with better clinical outcomes for certain patient subgroups. Professional societies have an important role to play in endorsing educational strategies and in clarifying and assessing the adequacy of patient knowledge.