Heart failure is a clinical syndrome characterized by inadequate cardiac performance under existing workload conditions (Gleland et al, 2000). The overall prevalence of heart failure is 3 - 20 per 1000 live births. The annual incidence of heart failure is 1 - 5 per 1000 live births (Davies et al, 2000). The aim of this work was to assess the clinical findings and the magnitude of the problem of heart failure in Yemen, and to find its relation with the level of serum adrenomedullin. That is through studying the cardiological causes of heart failure among the cases attending the main four hospitals in Sana'a during the period from October/2001 to October /2003. The inclusion criteria were; all cases with heart failure of cardiac etiology, at any age or sex. The exclusion criteria were; all cases with heart failure due to non-cardiological causes. All the studied cases were subjected to the following; full history and clinical examination, laboratory investigations including especially serum adrenomedullin level, chest x-ray, ECG, and ECHO. The data were analyzed and results showed that RHD and CHD were the major cardiological causes of HF in Yemen followed by MYHD then arrhythmia. The level of serum AM was highest among RHD group. The mitral valve was the most affected valve in RHD cases. Serum AM level was higher among patients with combined mitral and aortic valves affection than those with an isolated valve affection. In CHD, the ratio of the acyanotic CHD to the cyanotic CHD was approximately (2 : 1). Serum AM was higher among the cyanotic CHD cases than the acyanotic CHD. DCMP represented the majority of MYHD group cases followed by myocarditis. Serum AM level was higher among DCMP cases than myocarditis cases. The arrhythmia group includes a case with SVT. Heart failure was most apparent among children and infants. The highest level of serum AM was among children age group. There was slight male predominance with no significant relation with AM level. Most of the cases were in severe HF. Serum AM increased proportionately with the increase in the severity of HF. The case fatality rate was (7.5%) of the cases most of them were children. The level of serum AM was higher among the cases that died later on.