Objective: The Metabolic syndrome (MS) is characterized by a collection of risk factors, that increase the chance of developing cardiovascular complications. Classifications and definitions of the MS indicate that on its pathogenesis, as well as on resulting complications, five fundamental componets do participate – obesity, insulin resistance, endothelial dysfunction, aggregation of other components and diurnal pattern loss. The aim of our study was to detect changes in diurnal trait depending on the presence of metabolic syndrome. Design and method: Under the conditions of hospitalization we examined 56 persons with the presence of metabolic syndrome (average age 66 years) and 51 persons without metabolic syndrome (average age 61 years). To control the effectiveness of antihypertensive treatment, we used ambulatory blood pressure monitoring (ABPM) (Meditech and Marquette-Hellige devices) with oscillometric blood pressure measurement. Results: In the group of patients with MS dipping was present in 37.5 %, while in the group without MS in 57.1 %. Non dippers and risers where in the group with MS present in 58.9 %, while in the group without MS in 33.3 %. Monotherapy in patients with MS was present in 19.6 %, while in the group of patients without MS in 36.4 %. Four-combination of antihypertensives was in the group with MS in 23.2 %, while in patients without MS in 9.1 %. The mean blood pressure values in the group with MS were 134/79 mmHg and in the group without MS 132/83 mmHg. These blood pressure values were justifiably achieved due to differences in antihypertensive medication – monotherapy versus combination therapy. Conclusions: ABPM plays an important role in monitoring the effectiveness of antihypertensive treatment. In patients with MS achieving blood pressure targets is often a therapeutic problem, which usually requires a combination of three or more antihypertensives. Also presence of orthostatic hypotension, as a manifestation of cardiovascular autonomic neuropathy, may affect the treatment of arterial hypertension. Frequent loss of diurnal pattern in patients with MS is also of prognostic significance.