Abstract. Introduction: Selenium (Se) is an essential element that plays an important role in antioxidative protection against free radical damage. Its deficiency has been associated with several pathological conditions such as degenerative diseases, cancer, and schizophrenia. Indeed, accumulated evidences suggest that Se and selenoproteins have a protective role against the development and progression of cardiovascular disease, the largest single cause of death in schizophrenia. Objective: The aim of this paper was to assess the Se status of a group of schizophrenic patients. Materials and methods: Considering that Se concentration in human blood varies widely between geographical areas, we have also analyzed the serum Se concentration and the activity of its related antioxidant enzyme glutathione peroxidase (GPx) in 65 outpatients with a DSM-IV diagnosis of schizophrenia and in 106 healthy subjects residing in the same geographical area. All patients were recruited from Hospital Clínic of Barcelona, Spain. Results: The results show that in the control group, Se serum concentrations were 87.0 µg/L (IQR = 76.0 – 102.8). These values can be considered within the safe limits since no subject was found with concentrations lower than the threshold 45 µg/L. In schizophrenic patients, median serum Se concentrations were 79.0 µg/L (IQR = 69.0 – 86.0). In contrast to the control group, some of them had Se serum concentrations lower than the safe value. The GPx activity was 19.2 ± 7.4 IU/gHb for the control group and 14.7 ± 4.6 IU/gHb for patients. Conclusion: A strong positive correlation was found between serum Se concentrations and GPx activity in both groups. A statistically significant drop was observed in schizophrenic patients compared to age-matched controls (p < 0.05).