Objective The lack of nocturnal decline in blood pressure (BP) is associated with an increase in cardiovascular events. Soluble CD40 ligand (sCD40L) is involved in the pathogenesis of risk factor-related vascular damage. The purpose of this study was to examine the relationship between vascular endothelial functions, carotid intimamedia thickness (cIMT), plasma sCD40L levels and circadian BP profile in patients with essential hypertension. Material and methods The study population consisted of 81 essential hypertensive out-patients. BP dipping was defined as a night-to-day systolic and diastolic decrease >= 10%. Forty-seven dipper and 34 nondipper patients were compared. High sensitivity C-reactive protein (hs-CRP), sCD40L and urinary albumin were measured. Brachial artery flow-mediated dilatation (FMD) and cIMT was compared between the groups. Results sCD40L level (3.28 +/- 2.08 and 2.30 +/- 1.99 ng/ml, respectively, P = 0.036) and urinary albumin concentration (36.7 +/- 20.1 and 23 +/- 29.7 mg/l, respectively, P < 0.0001) were higher in nondippers than in dippers. Serum hs-CRP levels were not significantly different. FMD was found higher in dippers than nondippers (11.8 +/- 3.9% and 6.6 +/- 2.2%, respectively, P < 0.0001). The average cIMT was significantly higher in nondippers than dippers (0.928 +/- 0.060 Vs. 0.734 +/- 0.134 mm; P < 0.0001). Conclusions Nondipper patern has an additional negative effect on endothelial functions in hypertensive patients. Nondippers have enhanced sCD40L levels, which may contribute to their increased susceptibility to develop vascular damage.