The aims of our prospective study were to determine the development and natural history of esophogeal varices and variceal bleeding in patients with primary biliary cirrhosis. As part of a controlled clinical study, 265 patients with primary biliary cirrhosis who did not have esophageal varices at entry were followed for a median of 5.6 yr. The mean age was 49 yr (range 26–75 yr), 89% were women, and 69% had advanced histologic stage disease (stage 3–4) on liver biopsy at study entry. All patients were screened annually for esophageal varices by barium esophogram or endoscopy, or both; endoscopy was used to diagnose all episodes of esophageal variceal bleeding. Esophageal varices developed in 83 (31%) patients, and 40 (48%) of those with esophageal varices experienced one or more episodes of esophageal variceal bleeding. Cox regression analysis indicated that only serum bilirubin and histologic stage were associated independently with time to development of esophageal varices. In patients who developed esophageal varices, 33% and 41% developed esophageal variceal bleeding at 1 and 3 yr, respectively. After development of esophageal varices, 1- and 3-yr survival estimates were 83% and 59%, respectively. After the initial variceal bleeding episode, survival estimates were 65% and 46% at 1 and 3 yr and were dependent on Child's classification. These findings are important in considering indications for prophylactic therapy for esophageal varices in primary biliary cirrhosis and may influence timing of liver transplantation.