Background Excessive absorption of cobalt has been associated with cases of dilated cardiomyopathy in the past, but it is unclear whether occupationally exposed populations are at risk. Objective To assess the possible relationship between occupational exposure to cobalt and incipient signs of dilated cardiomyopathy. Methods A cross-sectional survey was conducted in a cobalt production facility in Belgium constituting one of the largest occupational populations worldwide (n=256 male workers). Exposure to cobalt was assessed by measuring urinary cobalt concentration (µg/g creat ), reflecting recent exposure, and by computing an integrated exposure index (µg/g creat ×years), reflecting long-term exposure. The effect on the myocardium was investigated by echocardiography and electrocardiography, and dose–effect relations with cobalt exposure were traced by multiple regression analysis. Results No dose–effect relationship between exposure to cobalt and parameters reflecting dilated cardiomyopathy was found in a population of workers characterised by a median recent cobalturia of 4 µg/g creat and a median long-term cobalturia of 100 µg/g creat ×years. A reduction in the dimensions of the left ventricular internal cavity was associated with recent exposure to cobalt. Conclusions Occupational exposure to cobalt does not appear associated with incipient signs of dilated cardiomyopathy within the gradient of exposure recorded in this population.