Objective:To characterize opportunities to postprescriptively modify antibiotic prescriptions initiated for treatment of suspected urinary tract infection (UTI) in nursing homes.Design:Cross-sectional cohort study.Methods:Data from the health records of residents treated for UTI between 2013 and 2014 in 5 Wisconsin nursing homes were abstracted using a structured approach. Explicit definitions were used to identify whether the prescribed antibiotic could have been stopped, shortened, or changed to a nonfluoroquinolone alternative. Antibiotic treatments appropriately modified by study nursing home providers in real time were not considered modifiable. Identification of >1 potential modification opportunity (eg, stop and shorten) per antibiotic treatment event was permitted.Results:In total, 356 eligible antibiotic treatment courses among 249 unique residents were identified. Only 59 antibiotic courses prescribed for treatment of suspected UTI (16.6%) were not amenable to any modification. Discontinuation of treatment due to lack of signs or symptoms of infection was the most frequently identified potential modification opportunity (66.2%). Although less common, substantial numbers of antibiotic treatment courses were potentially amenable to shortening (34%) or agent change (19%) modifications. If applied in concert at 72 hours after antibiotic initiation, stop and shorten modifications could eradicate up to 1,326 avoidable antibiotic days, and change modifications could remove a 32 remaining avoidable fluoroquinolone days.Conclusions:Substantial opportunity exists to enhance the quality of antibiotic prescribing for treatment of suspected UTI in nursing homes through postprescriptive review interventions. Additional studies examining how to best design and implement postprescriptive review interventions in nursing homes are needed.