Background: Heart failure (HF) is a life-threatening condition and optimal handling is necessary to reduce risk of therapy failure. The impact of the duration of HF diagnosis on HF outcome has not previously been examined. The objectives of this study were (I) to evaluate the impact of patient age on clinical outcomes, (II) to evaluate the impact of duration of the HF disease on outcomes, and (III) to evaluate the impact of age and HF duration on B-type Natriuretic Peptide (BNP) concentration in a population of HF patients. Methods and results: In the UPSTEP (Use of PeptideS in Tailoring hEart failure Project) study we retrospectively evaluated how age and HF duration affected HF outcome. HF duration was divided into < 1 year, 1-5 years and > 5 years. A multivariate Cox proportional hazard regression analysis showed that HF duration influenced outcome more than age, even when adjusted for comorbidities(< 1 year versus > 5 years: HR 1.65; 95% CI 1.28-2.14; P < 0.0002) on HF mortality and hospitalisations. The influence of age on BNP showed increased BNP as age increased. However, there was a significant effect on BNP concentration when comparing HF duration of less than one year to HF duration to more than five years, even when adjusted for age. Conclusions: Patients with longer HF duration had significantly worse outcome compared to those with short HF duration, even when adjusted for patient age and comorbidities. Age did not influence outcome but had an impact on BNP concentration; however, BNP concentration increased as HF duration increased.