Background: Endosonography [endoscopic ultrasound (EUS)-guided fine needle aspiration and endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration] is increasingly used for lung cancer staging and the assessment of sarcoidosis. Serious adverse events (SAE) have been reported in case reports, but the true incidence of complications is yet unknown. Objectives: To assess the rate of SAE related to endosonography and to investigate associated risk factors. Materials and Methods: PubMed, EMBASE and Cochrane libraries were searched for eligible references up to April 2012 and these included studies reporting on linear EUS or EBUS for the analysis of mediastinal/hilar nodal or central intrapulmonary lesions. Case series describing complications were excluded. Reported complications were classified into SAE or minor adverse events (AE). Results: 190 studies met the inclusion criteria. Information on follow-up was missing in half of the studies. In 16,181 patients, 23 SAE (0.14%) and 35 AE (0.22%) were reported. No mortality was observed. SAE were more frequent in patients investigated with EUS (0.30%) than in those investigated with EBUS (0.05%). Infectious SAE were most prevalent (0.07%) and predominantly occurred in patients with cystic lesions and sarcoidosis. In lung cancer patients, complications were rare. Discussion: Endosonography for intrathoracic nodal assessment seems safe for lung cancer patients and mortality has not been reported. For cystic lesions and sarcoidosis, there may be a small, but nonnegligible risk of infectious complications. The true incidence of SAE might be higher as accurate documentation of complications is missing in most studies.