The aim of this study is to investigate the effects of angiotensin-converting enzyme (ACE) inhibitors and furosemide on zinc metabolism by assessing serum zinc and urine levels in hospitalized subjects. We recruited 11 patients with heart failure from the Internal Medicine Department; these patients had been hospitalized less than 72 h before. Heart failure was defined using clinical and radiological signs. Serum zinc concentrations were measured using an air/acetylene flame atomic absorption spectrophotometer. Urine zinc levels were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Data were obtained from the 11 patients and 24 healthy controls matched for age and sex. Results indicate higher urine zinc levels and lower concentrations of zinc in serum in heart failure patients vs matched controls (p<0.05). This study suggests that treating heart failure patients with ACE inhibitors may result in zinc deficiency.