The presence of medial arterial calcification (MAC), often referred to as Moncheberg's sclerosis, was sought in patients with long-standing diabetes mellitus. One hundred patients aged 22-50 years were initially divided into two groups, those with neuropathy and those without. As expected, the incidence of MAC was significantly higher in the neuropathy group (40% vs. 20%). When the patients were divided into two groups, those with MAC and those without, it appeared that the incidence of MAC was very high in patients who had microalbuminuria (57% vs. 13%) and particularly when microalbuminuria was combined with neuropathy (40% vs. 7%). It is concluded that microalbuminuria is a strong predicting factor of medial arterial sclerosis independent of neuropathy.