Foot problems are a major cause of morbidity in people with diabetes. Plantar callus is common and is a sign of abnormal foot pressures. Shear stresses at these areas of high foot pressures may ultimately result in ulcer formation. This study compared the effect on plantar callus of the use of rigid orthotic devices and conventional podiatric care. Twenty diabetic subjects participated in the study and were randomly allocated to conventional treatment (n = 11) or orthotic device treatment (n = 9). After 12 months the patients in the orthotic group showed a significant reduction in callus grade, whereas the conventionally treated group showed no significant change. There were no adverse effects from wearing the orthotic device. Rigid orthoses have a beneficial effect on plantar callus presumably through the lowering and redistribution of abnormal foot pressures.