Objectives:
To create a Polish adaptation of the Brief Negative Symptom Scale (BNSS), to assess the internal consistency of the Polish version of the BNSS, and to make correlations between the BNSS scores and the Positive and Negative Syndrome Scale (PANSS) in the group of patients with schizophrenia.

Methods:
The procedure of Polish adaptation of the assessment form (Scoresheet) of the BNSS, comprising 13 items organized in 6 subscales (anhedonia, lack of proper distress, asociality, avolition, blunted affect, and alogia), as well as the Manual and the Workbook of the scale was carried out. Psychometric tests were performed in 40 patients with paranoid schizophrenia (20 men and 20 women), aged 44±13 years, with illness duration of 17±10 years, and severity of symptoms on the PANSS 56±16 points, receiving unchanged pharmacological treatment in the last three months.

Results:
The Polish version was accepted by the authors of the scale. The reliability analysis showed high values of the Cronbach’s alpha coefficient both for the whole scale (0.97) and for individual subscales (0.74–0.93). The BNSS and its subscales showed a high significant correlation with the total PANSS score and with the PANSS negative symptom subscale, both original and modified.

Conclusions:
The obtained results indicate good psychometric properties of the Polish version of the BNSS and its possible usefulness in the study of negative symptoms of schizophrenia conducted in Poland.