Background. Patients with schizophrenia show mild or moderate cognitive impairment compared to healthy subjects. Cognitive impairment occurs even before the onset of psychotic symptoms and it is a key determinant of future development of the individual. Early intervention in psychosis is a mandatory approach for both individuals who are in the early years of the disease and for those groups at risk for schizophrenia. Objectives. The aim of the study was to assess cognitive performance in patients with schizophrenia and persecutory delusion. Methods. Study was performed in Psychiatry and Neurology Hospital of Brasov during 2010 – 2012. The study group consisted in 120 patients with a diagnosis of schizophrenia according to DSM-IVTR [13], aged 18 – 45 years. Comparative analysis was done with a control group of 60 healthy individuals recruited from the medical staff of the hospital. Positive and Negative Symptom Assessment was done using the PANSS scale and the analysis of persecutory delusion was made with PSYRATS scale. Cognitive assessment was done with MATRICS Consensus Cognitive Battery (MCCB). There were collected data regarding demographics, treatment and education. Results. There were statistically significant differences between men and women for BACS-SC (p = 0.002), HVLT-R (p = 0.0003) and NAB (p = 0.00001). Cognitive performance among patients with schizophrenia was lower than healthy controls in all areas. Conclusions. Patients with schizophrenia and persecutory delusion present cognitive deficits in all investigated areas. Their performances are significantly lower compared to the healthy population. Antipsychotics differ in terms of processing speed, reasoning and problem solving. Improving and maintaining cognitive ability must be priority therapeutic targets in treating schizophrenia.