Aims Several clinical conditions may precipitate acute heart failure (AHF) and influence clinical outcome. In this study we hypothesized that precipitating factors are independently associated with 90-day risk of death in AHF. Methods and results The study population consisted of 15 828 AHF patients from Europe and Asia. The primary outcome was 90-day all-cause mortality according to identified precipitating factors of AHF [acute coronary syndrome (ACS), infection, atrial fibrillation (AF), hypertension, and non-compliance]. Mortality at 90 days was 15.8%. AHF precipitated by ACS or by infection showed increased 90-day risk of death compared with AHF without identified precipitants [hazard ratio (HR) 1.69, 95% confidence interval (CI) 1.44-1.97, P < 0.001; and HR 1.51, 95% CI 1.18-1.92, P = 0.001), while AHF precipitated by AF showed lower 90-day risk of death (HR 0.56, 95% CI 0.42-0.75, P < 0.001), after multivariable adjustment. The risk of death in AHF precipitated by ACS was the highest during the first week after admission, while in AHF precipitated by infection the risk of death had a delayed peak at week 3. In AHF precipitated by AF, a trend toward reduced risk of death during the first weeks was shown. At weeks 5-6, AHF precipitated by ACS, infection, or AF showed similar risk of death to that of AHF without identified precipitants. Conclusions Precipitating factors are independently associated with 90-day mortality in AHF. AHF precipitated by ACS or infection is independently associated with higher, while AHF precipitated by AF is associated with lower 90-day risk of death.