BACKGROUND: Acute decompensated heart failure (ADHF) contributes adversely to health-related outcomes. Anorexia, early satiety, high metabolic rates, malnutrition, advanced age, and diuretic use characterise ADHF. This necessitated evaluating the correlates of low serum thiamine levels among ADHF patients in our facility. METHODS: This was a case-control study. One hundred and ten participants (55 AHF patients with 55 age and sex-matched healthy controls) were recruited consecutively. All participants had a physical examination, resting 12-lead ECG, 2D transthoracic echocardiography and baseline laboratory investigations and serum thiamine. Data analysis was done using STATA 13.1. RESULTS: The mean age of the study population was 45 (± 13.7) years. The mean serum thiamine levels among the ADHF and controls were 116.7 ± 31.6 nmol/L and 124.4 ± 29.8 nmol/L, respectively. Male gender, resting ECG QRS duration, and serum NT-proBNP independently predicted serum thiamine levels. CONCLUSION: In this study, male gender, NT-proBNP and QRS duration independently predicted serum thiamine levels.