Introduction Anticholinergic medications are associated with adverse outcomes in older adults and should be prescribed cautiously. We describe the Anticholinergic Risk Scale (ARS) scores of older inpatients and associations with outcomes. Methods We included all emergency, first admissions of adults >/=65 years old admitted to one hospital over 4 years. Demographics, discharge specialty, dementia/ history of cognitive concern, illness acuity and medications were retrieved from electronic records. ARS scores were calculated as the sum of anticholinergic potential for each medication (0=limited/none; 1=moderate; 2=strong and 3=very strong). We categorised patients based on admission ARS score (ARS=0 [reference]; ARS=1; ARS=2; ARS>/=3) and change in ARS score from admission to discharge (admission and discharge ARS=0 [reference]; same; decreased; increased). We described anticholinergic prescribing patterns by discharge specialty and explored multivariable associations between ARS score categories and mortality using logistic regression (Odds ratios (OR), 95% confidence intervals). Results From 33,360 patients, 10,183 (31%) were prescribed an anticholinergic medication on admission. Mean admission ARS scores were: Cardiology and Stroke=0.56; General medicine=0.78; Geriatric Medicine=0.83; Other medicine=0.81; Trauma and Orthopaedics=0.66; Other surgery=0.65. Mean ARS did not increase from admission to discharge in any specialty but reductions varied significantly from 4.6% (Other Surgery) to 27.7% (Geriatric Medicine) (p<0.001). The odds of both 30-day inpatient and 30-day post-discharge mortality increased with admission ARS=1 (OR=1.21, 95%CI 1.01-1.44 and OR=1.44, 1.18-1.74) but not with ARS=2 or ARS>/=3. The odds of 30- day post-discharge mortality were higher in all ARS change categories, relative to no anticholinergic exposure (Same: OR=1.45, 1.21-1.74, Decreased: OR=1.27, 1.01-1.57, Increased: OR=2.48, 1.98-3.08). Conclusion The inconsistent dose-response associations with mortality may be due to confounding and measurement error which may be addressed by a prospective trial. Definitive evidence for this prevalent modifiable risk factor is required to support clinician behaviour-change, thus reducing variation in anticholinergic deprescribing by inpatient speciality.