Using thermography, skin temperature was evaluated in a 76-year-old patient with type II diabetes mellitus, presenting with diabetic foot ulceration on the right hallux and a corn on the left fourth toe. Increased skin temperature was observed in both the right hallux and the left fourth toe, though there were no visible clinical signs of infection. Unexpectedly, the high temperature area was seen to extend from the left fourth toe to the ankle. The patient was later diagnosed with osteomyelitis, due to the presence of a high-intensity area on T2-weighted magnetic resonance imaging, suggesting the elevated skin temperature was due to osteomyelitis. Based on these observations, thermography could prove useful for screening for foot ulcers with osteomyelitis.