Empyema, or pus in the pleural cavity, is a well-known complication of bacterial pneumonia caused by direct invasion of bacteria into the pleural cavity. It was first described by Hippocrates around 500 bc and has been well recognized throughout medical history. However, since 1976, numerous reports have described an unusual form of pleural fluid infection in the absence of underlying pneumonia. This condition has been mainly seen in patients with decompensated cirrhosis. In view of the absence of a contiguous infection, and perhaps by analogy with spontaneous bacterial peritonitis (SBP), the term spontaneous bacterial empyema (SBEM) was coined for this disease. SBEM has not been studied as extensively as SBP, despite the fact that it may confer a high mortality rate. This discrepancy leads to these questions: Does SBEM exist? Since underlying liver disease is common to both SBP and SBEM, is SBEM simply a direct extension of underlying SBP? Is it a complication of bacterial pneumonia? Or is it an independent clinical condition?