BACKGROUND Patients admitted with acute exacerbation of chronic obstructive pulmonary disease (COPD) are often prescribed ipratropium bromide in combination with a beta 2 agonist such as salbutamol. Studies have not shown any benefit in adding ipratropium bromide to salbutamol in acute exacerbations of COPD, but these studies have only assessed patients for 60-90 minutes and short term studies may not predict long term clinical response. Combination therapy with the two drugs was compared with salbutamol alone in the treatment of acute exacerbations of COPD during a hospital admission. METHODS Seventy patients admitted to hospital with an acute exacerbation of COPD were randomly allocated to receive either nebulised salbutamol 5 mg and ipratropium bromide 500 micrograms, or nebulised salbutamol 5 mg alone (all four times a day) on admission. All other treatment was prescribed at the discretion of the attending physician. Length of stay in hospital and spirometric values on days 1, 3, 7, 14, and discharge were assessed. Patients completed a subjective symptom score each day. RESULTS There was no difference between the two groups in the mean (SD) length of stay (salbutamol 10.5 (4.7) days, salbutamol + ipratropium bromide 11.8 (4.4) days; 95% CI -1.02 to 3.62). There was no difference in spirometric values on days 1, 3, 7, 14, or discharge between the two groups. The subjective improvement was similar with both treatments. CONCLUSIONS The routine addition of nebulised ipratropium bromide to salbutamol appears to be of no benefit in the treatment of acute exacerbations of COPD.