Aim Extended‐spectrum β‐lactamase (ESBL)‐producing Enterobacteriaceae is associated with a high mortality rate and increased medical care costs. Elderly patients might receive mechanical ventilation with respiratory treatment for the long term in respiratory care wards (RCW). This retrospective case–control study sought to determine the risk factors for geriatric patients who acquire a urinary tract infection with ESBL‐producing Escherichia coli or Klebsiella pneumoniae in this type of hospital. Methods Two RCW participated in this study from September 2006 to March 2007. Patients suspected of having a UTI were enrolled in this study. Urine samples were collected for culture. The medical records and demographic data of patients, including days of hospitalization, comorbidities and duration of invasive instruments, were recorded. UTI was diagnosed by physicians. ESBL‐producing isolates were detected using the phenotypic confirmatory tests according to the Clinical and Laboratory Standard Institute standards. Results There were 109 patients having 240 sets of clinical data and laboratory specimens. The prevalence of ESBL‐producing isolates of E. coli. and K. pneumoniae were 39.5% and 69.7%, respectively. Patients with multiple underlying comorbidities (OR = 2.88, P < 0.05) or receiving more than two antimicrobial agents (OR = 3.71, P < 0.05) were at an increased risk for acquiring the ESBL‐producing microorganisms after adjustment for sex, age and days of hospitalization. Conclusions Geriatric patients with recent exposure to two or more antibiotics and two or more numbers of comorbidities were at risk for ESBL‐producing organism infection. Our results suggest that infection control procedures in RCW should be concerned with reducing antimicrobial prescriptions and patient comorbidities. Geriatr Gerontol Int 2013; 13: 663–671.