A case of constrictive pericarditis with marantic endocarditis in a patient with the Noonan syndrome is reported. Congenital heart defects are often diagnosed in the Noonan syndrome and are undoubtedly the most problematic of its pathologies. Our patient had surgery for pulmonic stenosis at age 10 and 16 years. Over a period of 1-2 years prior to death at age 23 years, he developed elevated jugular venous pressure, hypoproteinaemia, pedal oedema and pleural effusions. The hypoproteinaemia and resulting signs were initially attributed to intestinal lymphangiectasia. The latter, unlike constrictive pericarditis, has been reported in the Noonan syndrome. Post-mortem examination revealed constrictive pericarditis with a marantic endocarditis. There was no evidence of intestinal lymphangiectasia.