Spontaneous bacterial peritonitis (SBP) is defined as infection of preexisting ascites without evidence for any intraabdominal source for secondary infection. SBP is now recognized with rising frequency and has mainly been reported in patients with alcohol-induced cirrhosis of the liver. We report SBP in a female dialysis patient whose ascites was not due to liver disease, but was possibly due to lupus erythematosus or represented 'nephrogenic ascites'. The patient had severe abdominal pain and a positive rebound phenomenon, fever and an elevated peripheral white cell count of 21,000 cells/microliters. Ascitic fluid analysis revealed an exudate with a protein concentration of 5.2 g/dl, 13,000 white cells/microliters with 94% neutrophils and positive cultures for Streptococcus morbillorum. Because of the dramatic clinical features the patient underwent laparotomy which did not reveal a source for secondary infection and in retrospect was unnecessary. The patient responded well to antibiotic therapy. This case report draws attention to SBP as a cause of acute abdomen in patients on chronic hemodialysis.