Tumor necrosis factor-alpha (TNF-alpha) level, tissue-typed plasminogen activator(t-PA) activity and PA inhibitor (PAI) activity were determined in three groups: (1) 25 NIDDM patients with silent myocardial ischemia (SMI) or silent cerebral ischemia (SCI); (2) 18NIDDM patients without SMI or SCI; (3) 20 age-matched normal controls. Diagnosis of SMI or SCI was based on the finding of ischemic evidence by SPECT of myocardiotomograph or cerebrotomograph. All patients ECG and blood pressure were normal, and they had no history of clinical symptoms and signs of MI or CI. The result showed that the TNF-alpha level and PAI activity in the ischemia group were the highest and the t-PA activity in the ischemia group was the lowest, as compared with those in the other two groups respectively. It suggests that in NIDDM patients who have high TNF-alpha, high PAI activity, low t-PA, and even no symptoms and signs of MI or CI, anticoagulant therapy might be useful to prevent the progression of diabetic macroangiopathies.