Objective: We investigated the possible association of intracellular cytokine profiles in peripheral mononuclear cells in whole blood from patients with carotid atherosclerosis in whom follow-up after carotid endarterectomy (CEA) showed the onset or progression of contralateral disease. Methods and results: Intracellular expression of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, interleukin (IL)-1 beta, IL-6, IL-8, IL-4 and IL-10 was determined in 43 patients with carotid atherosclerosis, at baseline and at 1, 3, 6 and 12 months after CEA, and in 16 healthy subjects. When follow-up ended patients were divided into two groups, those with cured or stable disease (no onset of disease or unchanged stenosis in the contralateral vessel) and those with progressive disease (onset of disease or increased stenosis in the contralateral vessel). In patients with cured or stable disease, cytokine-positive cells significantly decreased or remained unchanged (IL-8 and IL- 10) during follow-up, whereas in patients with progressive disease they increased or remained unchanged (TNF-alpha). Multivariate ANOVA confirmed that the trend of cytokine expression between baseline and 12 months differed significantly in the two groups. Conclusions: Intracellular expression of TNF-alpha, IFN-gamma, IL-1 beta, IL-6, IL-8, IL-4 and IL-10 in peripheral mononuclear cells is associated with the outcome of contralateral disease after CEA. (c) 2006 Elsevier Ireland Ltd. All rights reserved.