A 69-year-old man was hospitalized for exacerbation of chronic obstructive lung disease. Treatment with nebulized ipratropium bromide resulted in urinary retention that resolved once the drug was discontinued. Urinary retention is a rare complication of ipratropium bromide. Because all of the cases described in the literature occur in elderly men with prostate hypertrophy, the drug should be used cautiously in this group of patients.