Birgit L Seelen-de Lang,1 Christien E Boumans,2 Henk LI Nijman3 1Flexible Assertive Community Treatment-Team, GGZ Oost Brabant, Boekel, the Netherlands; 2Long-Term Clinical Care, GGZ Oost Brabant, Boekel, the Netherlands; 3Behavioural Science Institute, Radboud University, Nijmegen, the NetherlandsCorrespondence: Birgit L Seelen-de LangGGZ Oost Brabant, PO Box 3, Boekel 5427 ZG, the NetherlandsTel +31 6 52612286Email bl.seelen-delang@ggzoostbrabant.nlPurpose: The Brief Negative Symptom Scale (BNSS) was developed to measure negative symptoms of schizophrenia. However, the Dutch translation of this instrument, called the “Korte Schaal voor Negatieve Symptomen” (KSNS), has not yet been validated. This study investigates the validity and reliability of this Dutch version of the instrument.Patients and Methods: The Psychotic Symptom Rating Scale (PSYRATS), Calgary Depression Scale for Schizophrenia (CDSS), the Health of the Nation Scale (HoNOS) and the KSNS were used for routine outcome monitoring to measure symptoms in 28 patients with a psychotic disorder who were being treated on a long-stay ward.Results: The internal consistency of the KSNS is fair to good. The inter-rater reliability is excellent. The concurrent validity is moderate but acceptable. The correlations between the KSNS and scales for depression and positive symptoms were not significant, which indicate good divergent validity.Conclusion: Despite the small sample size of the current study, we conclude that the BNSS, called the KSNS in Dutch, appears to be a reliable and valid tool for investigating negative symptoms in detail in patients with psychotic disorders.Keywords: BNSS, Dutch translation, negative symptoms, schizophrenia, validation