In 1995, Light11 proposed a new classification scheme for empyema to include biochemical properties of pH < 7.0 or glucose < 40 mg/dL, positive culture or gram stain, or frank pus. Spontaneous bacterial “empyema” criteria define the pleural fluid as having transudate properties and do not require any of the criteria for an empyema to make the diagnosis.1 Despite this, there are a number of cases of SBEM that actually meet exudative criteria. In an analysis of 11 cases of SBEM, Xiol et al1 found that all instances met transudative pleural fluid characteristics; however, transudate was defined as having to meet at least two of Light’s criteria. If traditional Light’s criteria were applied, 45% of the SBEM cases would have been exudates. The distinction between SBEM and traditional empyema is important, because the treatments are different. Empyemas usually require urgent tube thoracostomy, whereas SBEM is generally treated with antibiotics alone.7,10 The name spontaneous bacterial “empyema” is at best misleading, because it is a transudate by definition and does not have to meet any commonly accepted definition of an empyema.