AIM: The aim of this paper was to determine the extent of use, duration and the most common dose of benzodiazepine in patients with schizophrenia, depression and PTSD. STUDY DESIGN: Cross–sectional study. PARTICIPANTS AND METHODS: The subjects were all patients with medical diagnoses of schizophrenia, depression and PTSD, who had been in treatment 3 years at minimum, and were hospitalized last year at the Department for Integrative Psychiatry of the Clinic for Psychiatry, Clinical Hospital Centre Osijek. The research was conducted by means of a comprehensive analysis of inpatient and outpatient documentation, and a data collection table was developed in cooperation with the supervisor. RESULTS: A total of 141 respondents participated in this study. Most of the respondents (98.6 %) use benzodiazepines in their therapy. The majority of respondents (60 %) are male. Males suffers the most from schizophrenia and PTSD (57 % and 95 %), while women suffers the most from depression (70 %). The majority of people who use benzodiazepines are aged 44 to 57 years of age. The range of years of treatment for these diagnoses is 5 to 12 years. Diazepam is the longest-used therapy, approximately 4 years, and flurazepam is the shortest. The majority of respondents use only one benzodiazepine (61.1 %), most commonly diazepam. Diazepam is used by 73 % of respondents and is the most commonly used therapy. Most people use benzodiazepines in normal daily doses, and only 14 out of the total number of respondents take doses higher than usual. CONCLUSION: The frequency of prescribing and administering benzodiazepines is extremely high. The largest number of people suffering from schizophrenia and PTSD are men, while significantly more women suffer from depression. Usage of benzodiazepines lasts much longer than it should. Diazepam is the benzodiazepine which is most commonly prescribed. Benzodiazepines are most commonly administered in usual daily doses.