Of 282 consecutive ascites prospectively collected in 54 months, Spontaneous Bacterial Peritonitis (SBP) was diagnosed in 8.5% of the cases, "probable" SBP in 31.1%, Bacteriascites (BA) in 3.5% and Sterile Ascites (SA) (negative ascitic fluid culture with PMN less than 250/mm3) in 74.8%. Escherichia Coli (41.6%) and Staphylococcus Epidermidis (60%) were the most frequent pathogens isolated in patients with SBP and BA, respectively. With regards to in-hospital mortality, 18% of patients with BA and 50% with SBP died; the mortality seemed to be related to the degree of hepatic and renal damage, to a higher peripheral and ascitic WBC concentration and to a lower pH of ascitic fluid (FA). When the comparative analysis was applied to the four groups of ascites, a different distribution of clinical signs and biohumoral parameters appeared. As a matter of fact, abdominal pain, fever and rebound tenderness resulted significantly more frequent in SBP and "probable" SBP. Furthermore, the mean values of peripheral and ascitic WBC concentration, of serum creatinine and of ALT were statistically higher in SBP and "probable" SBP than in SA and BA groups. The strict relationship, both symptomatologic and biochemical, between SA and BA on the one hand and between "probable" SBP and SBP on the other, prompted us to conclude that "probable" SBP and SBP represent different patterns of the same disease. Therefore, the subclassification in the four groups outlined above would not be in accordance with the clinical practice and could give rise to the physician's confusion and uncertainty.