It has recently been suggested that nonalcoholic steatohepatitis (NASH) is an under-recognized cause of cryptogenic cirrhosis (CC) on the basis of higher prevalence of obesity and type II diabetes among these patients. To test this hypothesis, we studied 65 consecutive patients with advanced cirrhosis (Child-Pugh Score >/= 7) of undetermined etiology (CC) from our active waiting list for liver transplantation in January 1993, 1996, and 1999. For each patient, we selected 2 age- and sex-matched controls from the corresponding lists. The prevalence of obesity (defined as body mass index [BMI] >/= 30) and diabetes were compared between the groups. Sixteen patients (and their 32 controls) with CC were excluded as further review of records suggested other possible etiologies. Thus, the final analysis included 49 patients and 98 controls. The etiology of cirrhosis in the control group was alcohol in 16.3%, chronic viral hepatitis in 30.6%, autoimmune hepatitis in 8.2%, and primary biliary cirrhosis (PBC) or primary sclerosing cholangitis in 35.7%. The prevalence of obesity (55% vs. 24%) and type II diabetes (47% vs. 22%) was significantly higher in patients with CC compared with controls. Twenty-three percent of patients with CC had both obesity and diabetes compared with 5% among controls (P =.002). There was no difference in the prevalence of hypercholesterolemia (serum cholesterol > 200 mg/dL) between the groups. In conclusion, patients with advanced CC are more likely to be obese and diabetic compared with age- and sex-matched patients with advanced cirrhosis. This supports the hypothesis that NASH may be an etiological factor in some of the patients with CC.