We assessed (i) the association between early arterial disease and factors linked to adiposity, dietary habits, and family in a young cohort of 151 obese children and adolescents with less than or equal to one cardiovascular (CV) risk factor, (ii) whether in subjects with carotid calcifications there was an imbalance of calcium-phosphorus homeostasis. Measurement included: carotid ultrasound, oral glucose tolerance test, anthropometry, body composition, dietary history, white blood cells count, lipids, uric acid, adiponectin, insulin, C-reactive protein, plasminogen activator inhibitor 1 (PAI-1), 25-hydroxyvitamin D, parathyroid hormone (PTH), calcium and phosphorus. Obese children with carotid artery intima media thickness (cIMT) values >75° percentile (0.55 mm), compared to those with lower cIMT, were more obese, more often pubertal and had higher prevalence of family history of CV disease (CVD) (P < 0.05), higher plasma PAI-1 and uric acid (P < 0.001) and lower adiponectin (P < 0.05) and high-density lipoprotein (HDL) cholesterol levels (P < 0.05). After adjustment for sex, age, puberty, obesity, and insulin levels, only PAI-I remained significantly different between the two groups (10.9 (7.2-29.8) vs. 6.2 (4.3-10.6) ng/ml, P < 0.001). Dietary intake did not affect cIMT values. Eight percent of subjects showed nonatherosclerotic carotid calcifications with patchy pattern. These children had a worse lipid profile (P < 0.05) and higher plasma PTH levels (48.6 ± 21.5 vs 38.5 ± 16.9 pg/ml, P < 0.05) that were inversely associated with 25-hydroxyvitamin D levels (r = 0.245, P < 0.01). Present results suggest that (i) several adiposity-related factors may play a role in promoting the development of early arterial diseases in young subjects with a benign phenotype of obesity, (ii) a PTH rise resulting from a subclinical imbalance in calcium-phosphorus homeostasis may affect the biological process of vascular calcifications.