Objectives: This study analyzed the prevalence of new psychoactive substance (NPS) use in the analyzed group and compared demographic features and psychoactive substance profiles between the 2 subgroups (NPS users, non-NPS users). The secondary measure was used to determine the prevalence of psychiatric comorbidities in study group and to compare demographic features and psychoactive substance profiles between 2 subgroups (the F11–19 only diagnosed group and the F11–19 group with psychiatric comorbidities according to ICD-10). Material and Methods: A 12-month retrospective cross-sectional analysis of medical records compiled for adult psychiatric patients who had been admitted to the Regional Psychiatric Hospital in Olsztyn, Poland, in October 1, 2016 – September 30, 2017 was conducted. After analyzing the available medical records, 157 cases were included and analyzed. Data for the study were collected in a specially designed monitoring card from discharge reports, including data from psychiatric examinations, especially anamnesis. Results: The most commonly declared psychoactive substances were amphetamine (AMF) – 54% and cannabinoids – 46%. The prevalence of NPS use in the study group was 34%. Inpatients taking NPS, as compared with non-NPS users, were younger and more often admitted to hospital through the Emergency Department. It was also found that NPS users more often took AMF or cannabinoids, and less frequently benzodiazepines (BDZ) or opioids. However, the taking of AMF, cannabinoids and BDZ was also age-dependent. Conclusions: The prevalence of psychiatric comorbidities in the study group was 9%. Inpatients with psychiatric comorbidities were older and took BDZ significantly more often than AMF. In addition, NPS use affects different groups, including a specific group as the analyzed sample, which shows a similar NPS use profile as different groups described in the literature. Int J Occup Med Environ Health. 2020;33(2):125–36