Distinguishing between osteomyelitis and neuropathic osteoarthropathy of the foot frequently presents a clinical and radiologic challenge in patients with diabetes. Magnetic resonance (MR) imaging was performed in 26 diabetic patients to observe changes in signal intensity in the complicated diabetic foot. In every patient with osteomyelitis (n = 13), signal intensity abnormalities were seen within the bone marrow (low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in 12 cases). Most of these patients had cortical lesions (n = 9) or associated soft-tissue infection (n = 12). Normal bone marrow signal intensity was observed in three of the four patients without osteomyelitis. Characteristic MR imaging findings (decreased signal intensity in bone marrow regardless of pulse sequence) were seen in patients with chronic neuropathic osteoarthropathy (n = 7), who were easily distinguished from patients with osteomyelitis. Conversely, in patients with acutely evolving neuropathic osteoarthropathy (n = 2), signal intensity changes within the bone marrow were similar to those observed in osteomyelitis, leading to potential diagnostic pitfalls. Familiarity with MR imaging findings observed in osteomyelitis and neuropathic osteoarthropathy can help identify these two entities, allowing early diagnosis and appropriate therapy.