Cardiovascular responses to cold pressor test and associated changes in blood concentrations of renin, aldosterone, and catecholamines were measured in 11 type I diabetic patients with microalbuminuria; 11 type I diabetic patients with normoalbuminuria matched for age, duration of diabetes, metabolic control; and in nine normal control subjects. Heart rate, renin, aldosterone, and catecholamines concentrations in diabetic patients and controls at baseline were similar, but higher mean blood pressure was evident in microalbuminuric than normoalbuminuric patients (p < 0.01) and controls (p < 0.05). Heart rate and mean blood pressure during cold pressor test in control subjects and type I diabetic patients increased significantly but similarly, regardless of the presence of microalbuminuria. Catecholamines, but not renin-aldosterone release, was associated to blood pressure modifications during the test. Peak values of mean blood pressure induced by cold test were positively correlated to baseline values in control subjects (r = 0.658, p < 0.05) and normoalbuminuric (r = 0.725, p < 0.01), but not microalbuminuric diabetics. These data suggest that the higher blood-pressure values at rest observed in microalbuminuric than normoalbuminuric diabetics are not associated with a higher cardiovascular response to cold hypertensive stimulus.