OBJECTIVES: Many of the anticholinergic medications are considered potentially inappropriate for use in the elderly because of their non-selective central and peripheral adverse effects. The objective of this study was to compare different anticholinergic drug scales in quantifying anticholinergic use in ambulatory elderly patients. METHODS: This retrospective cross-sectional study used National Ambulatory Medical Care Survey (NAMCS) 2010 data involving patients aged ≥ 65 years. The anticholinergic use was defined based on different anticholinergic scales: Anticholinergic Cognitive Burden (ACB), Anticholinergic Risk Scale (ARS), and Anticholinergic Drug Scale (ADS). All three scales classify drugs into three distinct levels based on their anticholinergic activity: level 1 (low), level 2 (moderate) and level 3 (high). Descriptive statistics was used to evaluate prevalence of anticholinergic use. Top five drugs within each level were also identified based. All analyses were adjusted for complex national survey design to evaluate prescribing rates. RESULTS: A total of 259 million office visits were made by elderly people in 2010. The overall anticholinergic use varied depending on the scale: ACB (36.7%), ARS (12.8%), and ADS (29.6%). The ACB estimated highest prevalence for level 3  drugs (7.2%), followed by ADS (5.9%) and ARS (4.9%). The prevalence for level 2 drugs was highest for ARS (4.0%) and lowest for ACB (1.6%). All three scales identified meclizine, diphenhydramine and amitriptyline among top five level 3 anticholinergic medications; cyclobenzaprine was among top five drugs in level 2 across different scales. Three scales differed in identifying other frequently used anticholinergics such as paroxetine, tolterodine, oxybutynin, and promethazine. CONCLUSIONS: There were substantial differences in quantifying anticholinergic use between three anticholinergic drug scales. There is a strong need to update and reconcile these scales to enhance its applicability in practice and research.