Very little is known about the atherosclerotic risk in patients with childhood-onset growth hormone deficiency (GHD). Such data may be relevant to reconstructing the natural course of the cardiovascular abnormalities associated with GHD. To this end, the intima-media thickness (IMT) of the carotid arteries and the vascular risk factors were evaluated in 14 childhood-onset GHD patients (age 25 +/- 1 yr, BMI 22 +/- 0.6 Kg/m2) and in 14 age-, sex-, and BMI-matched control subjects. IMT was greater in GHD patients (0.83 +/- 0.06 and 0.81 +/- 0.06 mmol/L for the right and left carotid artery) than in controls (0.64 +/- 0.03 and 0.64 +/- 0.04 mmol/L, P < 0.01 and P < 0.02, respectively). Serum total and lipoprotein cholesterol, and serum total triglycerides did not differ between the two groups. However, a significant increase in low density lipid triglycerides was present in GHD patients (0.27 +/- 0.02 mmol/L) compared with controls (0.19 +/- 0.01; P = 0.007). No difference was found in plasma fibrinogen and serum Lp(a) levels. Plasma glucose and insulin concentrations were similar in GHD and control subjects both in the fasted state and after an oral glucose load. In conclusion, young patients with childhood-onset GHD show an increased IMT in the absence of clear-cut abnormalities of the classic vascular risk factors. This suggests a role for GH deficiency per se in increasing the atherosclerotic risk.