The incidence of palsy in the third, sixth and seventh cranial nerves was studied with regard to central nervous system involvement in diabetic patients. Among 1961 diabetic patients, 19 (0.97%) demonstrated cranial nerve palsies. Nine out of these 19 patients showed facial palsy; 6 palsy of the oculomotor nerve; 2 palsy of the abducent nerve; and 3 both oculomotor and abducent nerve palsies. In contrast, only 5 out of 3841 non-diabetic patients (0.13%) had any cranial nerve palsies; all 5 were cases of facial palsy. The incidence of cranial palsies in diabetic patients was significantly higher than that in non-diabetic patients (P less than 0.01). Concerning age, sex, the state of glycemic control, diabetic complications and method of treatment, there were no differences disclosed in the diabetic patients with cranial nerve palsy. The incidences of diabetic complications were compared between the patients with facial palsy and those with ophthalmoplegia. Only one out of 9 patients with facial palsy (11%) had diabetic complications, whereas 7 out of 10 patients with ophthalmoplegia (70%) demonstrated diabetic complications and the difference was significant. Thus ophthalmoplegia appears to be more closely related to diabetic metabolism while facial palsy is less strongly correlated with diabetes.