This study was undertaken to establish the diagnostic efficiency of protected specimen brush (PSB) for identifying the etiologic agents in acute exacerbations of patients with bronchiectasis. A total of 38 randomly selected patients with proven bronchiectasis who presented with the symptoms of increase in daily amount and purulence of sputum were included in the study. The lower respiratory tract secretions were obtained via bronchoscopic PSB and inoculated onto blood agar, EMB agar, CHOC-VBC medium, Edward-Hayflick agar and regular diphasic medium. The isolated microorganisms were considered significant only if the 3 amount of growth was equal to or above 103cfu/ml. The microorganisms most commonly isolated were Streptococcus pneumoniae and Haemophilus influenzae, with a rate of 23.7% and 21.1% respectively. The PSB cultures of 11 (28,9%) patients yielded no growth. We conclude that PSB is an efficient method for identifying the bacteriological etiology of acute exacerbations in bronchiectatic patients. However, catious interpretation of the results and further studies to establish the sensitivity and specificity of the method should be made,