The authors present a case report of severe descending necrotizing mediastinitis (DNM) of posterior mediastinum, etiologically of vertebral osteomyelitis treated by the drainage through the posterior mediastinotomy. Mediastinitis caused by vertebral osteomyelitis is very rare. The most important diagnostic and surveillance tool for descending mediastinitis is a CT scan of chest and neck. Every surgical approach to the mediastinum has its advantages and disadvantages, so each patient has to be treated individually and the most suitable type of drainage must be chosen. The posterior mediastinotomy is an unusual alternative of drainage of pre- and paravertebrally localized DNM in posterior mediastinum but it is not recommended as a routine strategy.