In a retrospective review of 3,000 consecutive fibreoptic bronchoscopies, fifty were performed for investigation of lone pleural effusion. While 7 patients had bronchogenic carcinoma, in only one case was it visible endoscopically. In the absence of radiological or clinical features suggesting an endobronchial lesion, fibreoptic bronchoscopy is unlikely to aid in the diagnosis of lone pleural effusion.