A severe outbreak of lameness with joint and bone lesions and evidence of bacterial infection due to Enterococcus cecorum was diagnosed on a Dutch broiler farm. Morbidity and mortality were as high as 10%, while the remaining chickens performed well. Bacterial chondronecrosis and osteomyelitis with loosening of the femoral heads (femoral head necrosis) in the end stage was the most frequently observed lesion. The same pathological process was seen, though rarely, in the T3/T4 spine articulation. Septicemia resulting in pericarditis, local myositis and, most prominently, bone and joint lesions, was the major diagnosis. E. cecorum could be isolated from nearly all lesions when appropriate isolation methods (blood agar incubated in a carbon dioxide-enriched atmosphere) were used.