Background: The submaximal exercise testing, four hundred meters walking test (400mWT), respectively six minutes walking test (6MWT) were proposed as an alternative to classical exercise stress testing on cycloergometer in heart failure patients. Purpose: to compare 400mWT and 6 MWT between them, but also with classical exercise stress testing on cycloergometer, by using amino-terminal pro-B-type natriuretic peptide values (NT-proBNP) before and after exercise. Method: 20 patients were studied with systolic heart failure (LVEF<40%), 16 males and 4 females aged 37-70 years. After the relief of congestive syndrome, each patient was submitted, on three consecutive days, to a classical cycloergometer exercise stress testing, 6 MWT and 400mWT. Plasma NT- proBNP levels were measured at rest and also immediately after exercise by using ELISA method. Results: NT-proBNP values on three consecutive days were already increased at rest. During exercise, NT-proBNP increased for cycloergometer from 688±72 fmol/ml to 1868±91 fmol/ml (p<0.05), for 6MWT from 843±90 fmol/ml to 977±93 fmol/ml (15%, p<0.05) and for 400mWT from 676±63 fmol/ml to 927±95 fmol/ml (37%, p<0.05). The correlation of the peak values of NT-proBNP on cycloergometer /6 MWT and for cycloergometer/ 400mWT was r=0.71; for 400mWT/6MWT r=0.81, p<0.01 . Conclusion: NT-proBNP concentrations increase significantly and similarly in patients with chronic heart failure, both during maximal and submaximal exercise. The two submaximal tests from the current study have a sufficient intensity in order to stimulate the release of the natriuretic cardiac peptides and may be used as alternative approaches to maximal exercise testing.