The results of this general practice study suggest that acetylcysteine (Fabrol) administered orally for 2 months to patients with chronic bronchitis effectively changes the viscosity and character of sputum with resultant ease of expectoration and cough severity. There was a notable improvement in associated abnormal physical signs such as the presence of rhonchi, crepitations and symptoms including dyspnoea at rest. Tolerability was good, with 81% of patients experiencing no side-effects.