Asymmetric dimethylarginine (ADMA) plays a crucial role in the arginine-nitric oxide (NO) pathway. NO plays an important role in controlling vascular tone and regulates the contractile properties of cardiac myocytes. The purpose of this study was to investigate the effect of pharmacological treatment on asymmetrical dimethylarginine (ADMA) plasma levels in patients with acute congestive heart failure (HF). Patients with symptomatic acute congestive HF (NYHA Class III-IV) and impaired left ventricular (LV) function (ejection fraction less than 40 percent) were included in the study. ADMA and SDMA concentrations were assessed before and after pharmacological treatment in 18 critically ill patients on the intensive care unit by high performance liquid chromatography. All patients received a complete pharmacological treatment (diuretics, digoxin, ACE-inhibitors or angiotensin receptor blockers, and nitroglicerin) for the treatment of acute congestive HF. ADMA plasma levels of critically ill patients were significantly higher after pharmacological treatment respect baseline values (pre-treatment). In critically ill patients with acute congestive HF acute renal impairment function and the modulation of NOS determine plasma ADMA/SDMA levels after therapy.