Williams-Campbell syndrome is a unique type of bronchiectasis which shows ballooning during expiration and collapse during inspiration. Its etiology is thought to be a congenital decrease in bronchial cartilage. We experienced two adult cases of Williams-Campbell syndrome. Since the mucociliary transport system was normal in both cases and neither case had chronic sinusitis, these cases differed from sino-bronchial syndrome. Cases of Williams-Campbell syndrome reported in Japan show characteristic bronchography, but a decrease in bronchial cartilage may or may not be present and its congenital nature is very difficult to demonstrate. We therefore advocate referring to such cases of bronchiectasis with these bronchographic characteristics Williams-Campbell-type bronchiectasis, even if a decrease in bronchial cartilage is not observed.