Thirty-two thoracoscopies were performed in 28 horses. Sixteen horses were affected with pleuropneumonia whereas 12 were affected with various other thoracic conditions. The indications for thoracoscopy was diagnostic in 19 cases, therapeutic in 11 cases and both diagnostic and therapeutic in 2 cases. Twenty-six thoracoscopies were done standing whereas 6 were performed under general anaesthesia. The specific procedures performed during thoracoscopy were exploratory only (7), biopsy of the lung and lymph nodes (10), drain placement into pleural effusions (2) and abscesses (5), exploration prior to thoracotomy (2), transection of pleural adhesions and decortication (1) and window pericardectomy (2). Diaphragmatic hernia repair (2) and partial pneumonectomy (1) were initiated thoracoscopically but conversion to thoracotomy was necessary for completion. Standing thoracoscopy was well tolerated in most horses. Transient exacerbation of pulmonary compromise evidenced by tachypnoea was readily alleviated by reinflation of the lung. Standing thoracoscopy provided good visualisation of the dorsal and lateral structures of the thorax. The ventral thoracic structures and the cranial ventral diaphragmatic surfaces of the lungs were best visualised in dorsal or lateral recumbency under general anaesthesia. Thoracoscopy is a safe and useful diagnostic and therapeutic tool in horses with thoracic diseases.