Introduction: Many older patients experience polypharmacy and risk taking potentially inappropriate medications (PIMs) leading to adverse events. Recent studies have demonstrated the association between frailty and an increase in PIMs among community-dwelling older people and those with cancer. We evaluated whether frailty in hospitalised older patients is associated with polypharmacy and PIMs. \nMethods: A cross-sectional study of inpatients aged ≥70 years admitted to one UK hospital. Frailty was assessed using the Fried Frailty Phenotype and FRAIL Scale. Polypharmacy and hyper-polypharmacy were defined as the concomitant use of five + and 10 + medications, respectively. PIMs were identified using the Beers and STOPP criteria. \nResults: 201 participants (median age 80.7 years; 120 (60%) men) were recruited. 1738 medications were prescribed in this cohort, median 9 medications/ patient. Frailty was identified in 56% and 36% using the Fried Frailty Phenotype and FRAIL scale, respectively. Polypharmacy (46%) and hyper-polypharmacy (41%) were also common. Frailty using both scales was significantly associated with polypharmacy (P< 0.001). The Beers’ criteria identified 90 PIMs in 57 (28%) patients. 33 (58%) received one and 24 (42%) received 2+ PIMs. 108 PIMs in 76 (38%) patients were identified using the STOPP criteria. 53 patients (70%) received one and 23 (30%) received 2+ PIMs. Both frailty tools were significantly associated with PIMs using the STOPP criteria but not using the Beers’ criteria. \nConclusion: Frailty in older inpatients was significantly associated with polypharmacy and PIMs using the STOPP criteria. Structured medication review is essential for older people in hospital.