Ninety-five consecutive patients with constrictive pericarditis that was documented at the time of surgery during 1970 to 1985 were reviewed. The etiologies included idiopathic (42%), postradiotherapy (31%), post-cardiac surgery (11%), postinfective (6%), connective tissue disease-related (4%), neoplastic (3%) uremic (2%), and sarcoidosis (1%). Post-cardiac surgery etiology was seen only after 1980, but constituted 29% of cases during 1980–1985. Postradiotherapy etiology occurred with equal incidence in 1980–1985 and in 1970–1980, but the interval from radiotherapy to presentation with constrictive pericarditis was longer in the more recent period (11 vs 4.75 years). Effusive constrictive pericarditis occurred in 24% overall with similar prevalence in all of the etiologic groups except the postsurgical cases, which were caused by noneffusive fibrous constrictive pericarditis in all instances. Operative mortality was 12% overall: It was lower in the idiopathic group (8%) and higher in the postradiotherapy group (21%). Thus (1) postradiotherapy constrictive pericarditis continues to occur despite technical changes aimed at reducing its likelihood, but recent cases have a longer latent period: and (2) postsurgical constrictive pericarditis has emerged as an important etiology.