A prospective analysis was conducted to identify structural and biomechanical first ray abnormalities in consecutive diabetic patients presenting with their first great toe ulcer. Twenty-six patients (33 feet) met the inclusion criteria, with seven patients having bilateral hallux ulcers. There was no other history of ulcer, trauma, or surgery on the respective limb. Data were obtained during the patients' initial presentation with a great toe ulcer and included verbal history, standardized weight bearing radiographs, and standardized objective clinical measurements. Four patients (four feet) with subungual ulcers were included because of mechanical etiology. Twenty-four of the remaining 29 involved limbs exhibited gastrocnemius/soleus equinus and two other limbs had gastrocnemius equinus. Twenty-eight of 29 had structural hallux limitus. Twenty-four had hallux interphalangeal abductus. Twenty of the 33 ulcers were located plantar-medially at the interphalangeal joint area. Other frequent findings were first ray elevatus or dorsiflexion deformity (18 of 29), functional hallux limitus (14 of 29), interphalangeal joint sesamoid bone (13 of 29), hyperextended interphalangeal joint (13 of 29), and a prominent plantar-medial condyle of the proximalaspect of the distalphalanx (7 of 29). Halluxmalleus was less common (4 of 29), but consistently associated with plantar-distal tip ulceration. Metatarsus primus adductus was also infrequent (6 of 29). This study identifies and illustrates the importance of several biomechanical and structural factors present on initial presentation of great toe ulcers. Addressing these factors may improve the success of treatment and lessen the occurrence of this common and complex problem.