Introduction: In September 2013, at the Maripasoula Health Center (French Guiana), several gold miners sought medical care for lower limb edema (LLE) with signs of heart failure (HF). The objectives of the study were to investigate this presentation and identify its cause. Population and method: The study was prospective (September 2013–July 2014), descriptive, and single-center. Gold miners presenting with LLE and/or signs of HF and/or signs of polyneuropathy were included. Results: During the study, 42 individuals presented with symptoms of cardiomyopathy. The male-to-female ratio was 7.4, and the median age was 36 years (range 22–65). The main symptoms observed were: dyspnea in 60% (n=25/42), edema in 79% (n=33/42), signs of right-sided heart failure with jugular vein distension in 63% of cases (n=22/35) and/or hepatojugular reflux in 42% of cases (n=13/31). The diagnosis was beriberi, with the following distribution: 17 suspected cases (based on clinical findings), 15 probable cases (improvement after thiamine supplementation), and 10 biologically confirmed cases. The clinical forms were: wet 67% (n=28/42), mixed 31% (n=13/42), and shoshin beriberi 2% (n=1/42). The course of the disease was marked by improvement with treatment in 88% of cases (n=23/26), failure to recover in 8% (n=2/26), and one death was observed. The dietary survey revealed a low-calorie diet (average 1,106 kcal/day) with insufficient vitamin intake. Conclusion: This investigation confirmed the occurrence of a probable beriberi outbreak among gold miners in French Guiana. The multifactorial origin (intense physical activity, associated infections, precarious living conditions, diet based on polished white rice) could be better substantiated by an etiological study design such as a cohort or case-control study. However, efforts to implement and refine preventive measures in response to this highly concerning situation must continue.