Atherosclerosis is accelerated in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). We investigated a possible association of oxidized low-density lipoproteins (ox-LDLs), nitric oxide (NO), 3-nitrotyrosine, vitamin A, vitamin E, and β-carotene serum levels with subclinical atherosclerosis in RA and PsA. By the use of ELISA, we observed higher ox-LDL levels in patients with intima-media thickness (IMT) > 1 than in patients with IMT ≤ 1 and a negative correlation between NO levels and IMT values. By the use of high-performance liquid chromatography, we determined higher levels of vitamin A in patients with PsA and IMT ≤ 1 than in controls and lower levels of β-carotene in patients with RA and PsA than in controls. β-carotene concentrations were negatively correlated to the duration of disease in RA. Our study confirms that ox-LDLs and NO may be markers of accelerated atherosclerosis in RA and PsA whereas vitamins seem to be associated only to the presence of the autoimmune disorders.