It is recognized that diabetic patients with nephropathy frequently have macrovascular disease leaving them at risk of ischaemic foot lesions. In order to assess non-vascular risk factors for foot ulceration 64 patients were stratified into four groups: microalbuminuria, albuminuria with creatinine clearance greater than 40 ml min-1, chronic renal failure (clearance less than 40 ml min-1), and a non-nephropathic diabetic control group. Vibration perception threshold was measured by biothesiometry, peroneal nerve conduction velocity by conventional methods, and dynamic foot pressure by pedobarography. Vibration perception threshold was elevated in all three groups when compared with age-matched normal and diabetic control groups. Mean vibration perception threshold was 20.8 +/- 8.6 (+/- SD) in the microalbuminuria group (p less than 0.001 compared with age-matched normal control group), 28.1 +/- 5.6 (p less than 0.001) in the albuminuria group, 38.9 +/- 9.4 (p less than 0.001) in the renal failure group, 14.8 +/- 5.2 in the diabetic control group and 12.3 +/- 2.9 in the normal control group. Peroneal motor conduction velocity was reduced in all three groups when compared with normal control subjects, microalbuminuria 38.6 +/- 4.2 m s-1 (p less than 0.001), albuminuria 38.0 +/- 6.1 m s-1 (p less than 0.01), renal failure 35.5 +/- 1.2 m s-1 (p less than 0.001), diabetic control 40.6 +/- 1.8 m s-1, and normal 43.1 +/- 2.3 m s-1.(ABSTRACT TRUNCATED AT 250 WORDS)