To evaluate the benefits of conventional chest physiotherapy in acute bronchiolitis, 32 patients were allocated in a randomized controlled trial, 16 were given twice daily chest physiotherapy compared with 16 controls who were not given chest physiotherapy. The treatment group showed a mean clinical score for respiratory disability at admission of 5.56 (+/- 1.96), and 3.25 (+/- 1.27) when discharged. The control group presented a score of 5.75 (+/- 1.61) and 3.12 (+/- 1.30), p=0.77 and p=0.76 respectively. The mean length of illness in hospital in the treatment group was 4.00 (+/- 2.00) vs 3.87 (+/- 1.30) in the control group, p=0.84. Chest physiotherapy does not produce clinically important benefits in the treatment of acute bronchiolitis.